BUG: formatters ignored in to_html
- [x] I have checked that this issue has not already been reported.

- [x] I have confirmed this bug exists on the latest version of pandas.

- [ ] (optional) I have confirmed this bug exists on the master branch of pandas.

---

**Note**: Please read [this guide](https://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports) detailing how to provide the necessary information for us to reproduce your bug.

#### Code Sample, a copy-pastable example

```python
df = pd.DataFrame(dict(c1=pd.Series(range(3),dtype='int64'),
                       c2=pd.Series(range(3),dtype='Int64'),
                       c3=pd.Series(range(3),dtype='float64'),
                       c4=pd.Series(range(3),dtype='string'),
                       c5=pd.Series([0,1,0],dtype='bool'),
                       c6=pd.Series([0,1,0],dtype='boolean'),
                      ))

formatter = {c:lambda x: f"[{x}]" for c in df.columns}
display(HTML(df.to_html(formatters=formatter)))
```

  | c1 | c2 | c3 | c4 | c5 | c6
-- | -- | -- | -- | -- | -- | --
_| [0] | 0 | [0.0] | 0 | [False] | False
_| [1] | 1 | [1.0] | 1 | [True] | True
_| [2] | 2 | [2.0] | 2 | [False] | False



#### Problem description

DataFrame.to_html(formatters=formatters) is not working for MaskedArrays (new arrays with missing values)

#### Expected Output

formatters should also be applied to MaskedArrays.

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

<details>

INSTALLED VERSIONS
------------------
commit           : 2a7d3326dee660824a8433ffd01065f8ac37f7d6
python           : 3.8.5.final.0
python-bits      : 64
OS               : Linux
OS-release       : 4.19.76-linuxkit
Version          : #1 SMP Tue May 26 11:42:35 UTC 2020
machine          : x86_64
processor        : x86_64
byteorder        : little
LC_ALL           : en_US.UTF-8
LANG             : en_US.UTF-8
LOCALE           : en_US.UTF-8

pandas           : 1.1.2
numpy            : 1.19.1
pytz             : 2020.1
dateutil         : 2.8.1
pip              : 20.2.3
setuptools       : 49.6.0.post20200917
Cython           : 0.29.21
pytest           : 6.0.2
hypothesis       : None
sphinx           : None
blosc            : None
feather          : None
xlsxwriter       : 1.3.4
lxml.etree       : None
html5lib         : None
pymysql          : None
psycopg2         : None
jinja2           : 2.11.2
IPython          : 7.18.1
pandas_datareader: None
bs4              : 4.9.1
bottleneck       : 1.3.2
fsspec           : 0.8.2
fastparquet      : None
gcsfs            : None
matplotlib       : 3.2.2
numexpr          : 2.7.1
odfpy            : None
openpyxl         : 3.0.5
pandas_gbq       : None
pyarrow          : 1.0.1
pytables         : None
pyxlsb           : None
s3fs             : 0.2.2
scipy            : 1.5.2
sqlalchemy       : 1.3.19
tables           : 3.6.1
tabulate         : 0.8.7
xarray           : 0.16.1
xlrd             : 1.2.0
xlwt             : None
numba            : 0.48.0

</details>
