…ager to eval

This commit:

1. moves the definition of StreamIngestionManager and ReplicationStreamManager
to eval;
2. has planner implements functions in StreamIngestionManager and
ReplicationStreamManager, so that they won't take eval.Context and evalCtx.Txn
as parameters.

Release note: None

This commit is part of the effort of having an internal executor better bound
to its outer txn if there's one.

The next step after this commit is to replace the executor used in
`s.ptsProvider.GetState()` in `SQLTranslator.Translate()` to the one hanging
off `SQLTranslator`.

Release note: None