ENH: Create ArrowDtype
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).

Not activated yet. Opening to get any feedback about the approach cc @jbrockmendel 

discussed on the March call, id like to migrate from BaseMaskedDtype/NumericDtype etc to just MaskedDtype.  Similarly id suggest here just ArrowDtype. By "just ArrowDtype" you mean have `ArrowDtype` inherit directly from `ExtensionDtype`? > By "just ArrowDtype" you mean have ArrowDtype inherit directly from ExtensionDtype?

Right, without all the subclasses > * [x]  All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
> 
> Not activated yet. Opening to get any feedback about the approach cc @jbrockmendel
> 
> 1. `BaseArrowDtype` inherits from `BaseMaskedDtype`
> 2. `NumericArrowDtype` mirrors `NumericDtype`

can we rename NumericDtype -> NumericMaskedDtype (alt maybe NumericNumpyDtype and rename BaseMaskedDtype) > > * [x]   All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
> > 
> > Not activated yet. Opening to get any feedback about the approach cc @jbrockmendel
> > 
> > 1. `BaseArrowDtype` inherits from `BaseMaskedDtype`
> > 2. `NumericArrowDtype` mirrors `NumericDtype`
> 
> can we rename NumericDtype -> NumericMaskedDtype (alt maybe NumericNumpyDtype and rename BaseMaskedDtype)

This PR will just add the base ArrowDtype for now