Cleanup: .gitignore / __version__ strings / bunch of typos

[romanc]

Description

This clean-up PR contains three commits

1. Remove examples/mpi/.gitignore and merge its contents with the top-level .gitignore
2. Remove hard-coded __version__ strings from ndsl/{dsl, stencil}/__init__.py. The version there was 0.2.0, which - to me - looks like they were copied over from the pace repo.
3. Fix a bunch of typos throughout the codebase and the test cases. Most of it in comments, I rarely touched variable names.

How Has This Been Tested?

Covered by pre-commit hooks and existing test cases.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas: N/A
• I have made corresponding changes to the documentation: N/A
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules: N/A
• New check tests, if applicable, are included: N/A

[FlorianDeconinck]

LGTM

[bensonr]

much needed cleanup

[fmalatino]

lgtm