IntervalIndex.from_arrays/from_breaks does not accept categorical data with valid dtype
xref #21243

#### Code Sample, a copy-pastable example if possible
`IntervalIndex.from_arrays` fails:
```python
In [2]: cat_l = pd.Categorical([0, 0, 1, 2, 2])

In [3]: cat_r = pd.Categorical([1, 3, 3, 3, 4])

In [4]: pd.IntervalIndex.from_arrays(cat_l, cat_r)
---------------------------------------------------------------------------
TypeError: category, object, and string subtypes are not supported for IntervalIndex
```

`IntervalIndex.from_breaks` fails:
```python
In [5]: cat_breaks = pd.Categorical([0, 1, 2, 3])

In [6]: pd.IntervalIndex.from_breaks(cat_breaks)
---------------------------------------------------------------------------
TypeError: category, object, and string subtypes are not supported for IntervalIndex
```

`IntervalIndex.from_tuples` currently works, though is likely not tested:
```python
In [7]: cat_tup = pd.Categorical([(0, 1), (0, 1), (0, 3), (1, 2)])

In [8]: pd.IntervalIndex.from_tuples(cat_tup)
Out[8]:
IntervalIndex([(0, 1], (0, 1], (0, 3], (1, 2]]
              closed='right',
              dtype='interval[int64]')
```

`IntervalIndex.from_intervals` is deprecated, but will fail in the same way as described in #21243 since it hits the same code path.

The above examples also fail with `CategoricalIndex`.

Categorical data that is not of the appropriate dtype, e.g. strings, should still not be supported.

#### Problem description
An `IntervalIndex` cannot be created from categorical data with the appropriate dtype.  I doubt the failing examples shown above are very common, but #21243 seems like it'd be more common, and fixing it gives us this support for free.

#### Expected Output
I'd expect these to be successfully created (i.e. same result as building from the underlying list of data).

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

<details>

INSTALLED VERSIONS
------------------
commit: c85ab083919b59ce84c220d5baf7d34ff4a0bcf2
python: 3.6.1.final.0
python-bits: 64
OS: Windows
OS-release: 10
machine: AMD64
processor: Intel64 Family 6 Model 78 Stepping 3, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None
LOCALE: None.None

pandas: 0.24.0.dev0+42.gc85ab08
pytest: 3.1.2
pip: 9.0.1
setuptools: 39.0.1
Cython: 0.28.2
numpy: 1.13.3
scipy: 1.0.0
pyarrow: 0.6.0
xarray: 0.9.6
IPython: 6.1.0
sphinx: 1.5.6
patsy: 0.4.1
dateutil: 2.6.0
pytz: 2017.2
blosc: None
bottleneck: 1.2.1
tables: 3.4.2
numexpr: 2.6.4
feather: 0.4.0
matplotlib: 2.0.2
openpyxl: 2.4.8
xlrd: 1.1.0
xlwt: 1.3.0
xlsxwriter: 0.9.8
lxml: 3.8.0
bs4: None
html5lib: 0.999
sqlalchemy: 1.1.13
pymysql: None
psycopg2: None
jinja2: 2.9.6
s3fs: None
fastparquet: 0.1.5
pandas_gbq: None
pandas_datareader: None

</details>
