Add default repr for EAs
Closes https://github.com/pandas-dev/pandas/issues/22846
Closes https://github.com/pandas-dev/pandas/issues/23590

```python
In [4]: pd.core.arrays.period_array(['2000', '2001', None], freq='D')
Out[4]:
<PeriodArray>
['2000-01-01', '2001-01-01', 'NaT']
Length: 3, dtype: period[D]

In [5]: pd.core.arrays.period_array(['2000', '2001', None] * 100, freq='D')
Out[5]:
<PeriodArray>
['2000-01-01', '2001-01-01',        'NaT', '2000-01-01', '2001-01-01',
        'NaT', '2000-01-01', '2001-01-01',        'NaT', '2000-01-01',
 ...
        'NaT', '2000-01-01', '2001-01-01',        'NaT', '2000-01-01',
 '2001-01-01',        'NaT', '2000-01-01', '2001-01-01',        'NaT']
Length: 300, dtype: period[D]

In [6]: pd.core.arrays.integer_array([1, 2, None])
Out[6]:
<IntegerArray>
[1, 2, NaN]
Length: 3, dtype: Int64

In [7]: pd.core.arrays.integer_array([1, 2, None] * 1000)
Out[7]:
<IntegerArray>
[  1,   2, NaN,   1,   2, NaN,   1,   2, NaN,   1,
 ...
 NaN,   1,   2, NaN,   1,   2, NaN,   1,   2, NaN]
Length: 3000, dtype: Int64

```