ENH: Better error message when interpolating dtype integer with method="linear"
#### Is your feature request related to a problem?

When trying to interpolate a column with dtype integer with `method="linear"` the error message is not very descriptive (example to reproduce at the bottom of this issue):
```
ValueError: Invalid fill method. Expecting pad (ffill) or backfill (bfill). Got linear
```

As "linear" is the default interpolation method I think the error message should be more descriptive, even though IntegerArray is still experimental according to the [docs](https://pandas.pydata.org/pandas-docs/stable/user_guide/integer_na.html).

#### Describe the solution you'd like

I think the error message should include a hint to the potential cause that the array you're trying to interpolate is of dtype integer. Something like this could work:
```
ValueError: Invalid fill method. Expecting pad (ffill) or backfill (bfill). Got linear. Are you trying to interpolate an integer column?
```
I would be happy to create a PR with the improvement myself.

#### API breaking implications

As this only requires a change to the error message it does not break any API.

#### Describe alternatives you've considered

An alternative solution would be to implement linear interpolation for integer arrays but I suspect that that is not compatible/unexpected with some use-cases of integer arrays.

#### Additional context
Reproducable example:
```python
import pandas as pd


s = pd.Series([1, None, 3], dtype=pd.Int64Dtype())

s.interpolate(method="linear")
```
