Delete MANIFEST.in and exclude artifacts from sdist and wheel

[rly]

Now that we use hatch to build instead of setuptools, and hatch has its own way of specifying which files go into the sdist/wheel, MANIFEST.in is no longer used and can be deleted.

Analogous to https://github.com/NeurodataWithoutBorders/pynwb/pull/1902

Before switching to hatch, we included only certain files in the sdist/wheel (as shown in MANIFEST.in). Since switching to hatch, we include basically all files, which is unnecessary. So here I also exclude the ones we excluded previously.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 88.79%. Comparing base (2505a0e) to head (169b89e).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #1119 +/- ## ======================================= Coverage 88.79% 88.79% ======================================= Files 45 45 Lines 9774 9774 Branches 2776 2776 ======================================= Hits 8679 8679 Misses 778 778 Partials 317 317 ```

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