chore: deprecate `select_columns`

[ion-elgreco]

Which issue does this PR close?

• related https://github.com/apache/datafusion-python/issues/875

  Rationale for this change

  Aliases in my opinion bloat the API, in this case it's also just nearly the same as select so we can just deprecate it and only keep select as that is clear enough. This will also improve code readability when you look at datafusion code.

What changes are included in this PR?

• marks select_columns as deprecated

Are there any user-facing changes?

• marks select_columns as deprecated

[timsaucer]

We need to update docs in docs/source/user-guide/common-operations/select-and-filter.rst to no longer user select_columns since it's marked as deprecated

[ion-elgreco]

We need to update docs in docs/source/user-guide/common-operations/select-and-filter.rst to no longer user select_columns since it's marked as deprecated

Noted, will fix it once I'm back

[timsaucer]

These are trivial diffs, so I'll update them and ask @Michael-J-Ward to give a once over. Thank you again for all the PRs!

[Michael-J-Ward]

LGTM!