Consider removing the axom aliases to fixed width types

[gzagaris]

Axom defines the following aliases:

https://github.com/LLNL/axom/blob/fb2bb2a1f4e37e8a965e8799bca7896b64084e3a/src/axom/core/Types.hpp#L29-L46

This was mainly done in the past in order to support fixed width types with and without C++11.

Since, we now require C++11, these aliases are not needed. Instead, we can use the C++11 fixed width types directly in code.

[rhornung67]

Replace use of axom::type with std::type to avoid confusion and potential integration issues.

[rhornung67]

note in release notes for next release so users can prepare.

[kennyweiss]

We should investigate if type aliases can be marked as deprecated. If so, we should mark these as deprecated (to be removed in the release after the current one), and stop using them internally within axom.

[white238]

Done!