[IR] Add filter expression to Source node

[asfimport]

Add an optional filter expression to Source nodes to allow consumers that push predicates down to push them all the way to the source.

Reporter: Phillip Cloud / @cpcloud
Assignee: Phillip Cloud / @cpcloud

PRs and other links:

• GitHub Pull Request #11438

_{Note: This issue was originally created as ARROW-14350. Please see the migration documentation for further details.}