[mlir] Add support to SourceMgrDiagnosticHandler for filtering FileLineColLocs

This revision adds support for passing a functor to SourceMgrDiagnosticHandler for filtering out FileLineColLocs when emitting a diagnostic. More specifically, this can be useful in situations where there may be large CallSiteLocs with locations that aren't necessarily important/useful for users.

For now the filtering support is limited to FileLineColLocs, but conceptually we could allow filtering for all locations types if a need arises in the future.

Differential Revision: https://reviews.llvm.org/D103649