BUG: Cant access some `TimedeltaProperties` components directly
XREF: https://github.com/pandas-dev/pandas/pull/33208#discussion_r402181910

---

#### Note:

I'm using "hours" here for the examples, but this applies to

- hours
- minutes
- milliseconds

---

#### Short explanation:

Not all components are exposed directly:

Example:

```
In [1]: import pandas as pd                                                                                   

In [2]: s = pd.Series(pd.timedelta_range(start="1 day", periods=5, freq="H"))                                 

In [3]: s.dt.components                                                                                       
Out[3]: 
   days  hours  minutes  seconds  milliseconds  microseconds  nanoseconds
0     1      0        0        0             0             0            0
1     1      1        0        0             0             0            0
2     1      2        0        0             0             0            0
3     1      3        0        0             0             0            0
4     1      4        0        0             0             0            0

In [4]: s.dt.days                                                                                             
Out[4]: 
0    1
1    1
2    1
3    1
4    1
dtype: int64

In [5]: s.dt.hours                                                                                            
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-5-86f203890f2a> in <module>
----> 1 s.dt.hours

AttributeError: 'TimedeltaProperties' object has no attribute 'hours'
```


---

#### Long explanation:

If we create a series that contains a timedelta, we can access only some of the components directly.

Example setup:

```
In [1]: import pandas as pd                                                                                   

In [2]: s = pd.Series(pd.timedelta_range(start="1 day", periods=5, freq="H"))                                 

In [3]: s                                                                                                     
Out[3]: 
0   1 days 00:00:00
1   1 days 01:00:00
2   1 days 02:00:00
3   1 days 03:00:00
4   1 days 04:00:00
dtype: timedelta64[ns]

In [4]: s.dt.components                                                                                       
Out[4]: 
   days  hours  minutes  seconds  milliseconds  microseconds  nanoseconds
0     1      0        0        0             0             0            0
1     1      1        0        0             0             0            0
2     1      2        0        0             0             0            0
3     1      3        0        0             0             0            0
4     1      4        0        0             0             0            0
```

We can access "days" and "seconds" directly, for example:

```
In [5]: s.dt.days                                                                                             
Out[5]: 
0    1
1    1
2    1
3    1
4    1
dtype: int64

In [6]: s.dt.seconds                                                                                          
Out[6]: 
0        0
1     3600
2     7200
3    10800
4    14400
dtype: int64
```

But if we try to access "hours" for example directly:

```
In [7]: s.dt.hours                                                                                            
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-7-86f203890f2a> in <module>
----> 1 s.dt.hours

AttributeError: 'TimedeltaProperties' object has no attribute 'hours'
```

---

Output of ``` pd.show_versions() ```:

<details>

INSTALLED VERSIONS
------------------
commit           : 37dc5dc391333fede424964a3c8ab034318d6ed4
python           : 3.7.6.final.0
python-bits      : 64
OS               : Linux
OS-release       : 5.5.13.a-1-hardened
Version          : #1 SMP PREEMPT Wed, 25 Mar 2020 21:46:24 +0000
machine          : x86_64
processor        : 
byteorder        : little
LC_ALL           : None
LANG             : en_US.UTF-8
LOCALE           : en_US.UTF-8

pandas           : 1.1.0.dev0+1089.g37dc5dc39
numpy            : 1.18.1
pytz             : 2019.3
dateutil         : 2.8.1
pip              : 20.0.2
setuptools       : 46.0.0.post20200311
Cython           : 0.29.16
pytest           : 5.4.1
hypothesis       : 5.8.0
sphinx           : 2.4.4
blosc            : None
feather          : None
xlsxwriter       : 1.2.8
lxml.etree       : 4.5.0
html5lib         : 1.0.1
pymysql          : None
psycopg2         : None
jinja2           : 2.11.1
IPython          : 7.13.0
pandas_datareader: None
bs4              : 4.8.2
bottleneck       : 1.3.2
fastparquet      : 0.3.3
gcsfs            : None
matplotlib       : 3.2.1
numexpr          : 2.7.1
odfpy            : None
openpyxl         : 3.0.1
pandas_gbq       : None
pyarrow          : 0.16.0
pytables         : None
pyxlsb           : None
s3fs             : 0.4.2
scipy            : 1.4.1
sqlalchemy       : 1.3.15
tables           : 3.6.1
tabulate         : 0.8.7
xarray           : 0.15.1
xlrd             : 1.2.0
xlwt             : 1.3.0
numba            : 0.48.0

</details>