Expose a get_mv_candidates_for_table API for ViewMatcher

[xudong963]

The usage:

let view_matcher = ViewMatcher::try_new_from_state(&session_state).await?;
let table_ref = TableReference::bare("my_table");
let candidates = view_matcher.get_mv_candidates_for_table(&table_ref);

[xudong963]

@matthewmturner, as the comment says, the method will return a superset, if we want to return the exact candidates, the API could be complex or require users to give a SpjNormalForm, which is a bit hard to understand.

For our usecase, the current API should be enough, wdyt?