[NFC][analyzer] Introduce specialized variants of makeNode (#194459)
This commit introduces new methods `makePostStmtNode` and
`makeNodeWithBinding` of `CoreEngine`, which will be used instead of the
5-parameter overloads of `NodeBuilder::generateNode` and
`NodeBuilder::generateSink` (which were originally methods of the class
`StmtNodeBuilder` that was deleted in commit
fb46677a858697afa116c4252e84050a07bc6a70).
This commit applies the newly introduced methods in a few places (as
examples), but there are 80+ call sites that use the 5-parameter
`NodeBuilder::generateNode` or `generateSink`, so this transition will
be completed in multiple follow-up commits.
I decided to introduce these methods because after the transition there
will be 20+ calls to `makePostStmtNode` and 30+ calls to
`makeNodeWithBinding` and it would be cumbersome to use plain `makeNode`
instead of these specialized variants.
(On the other hand these new methods don't support specifying a `tag`
because only a few call sites would use that feature of the 5-parameter
`generateNode`.)