refactor: refactor series of visit_stream_node method

[wenym1]

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What's changed and what's your intention?

Currently we have only a visit_stream_node method to visit the stream node, which takes the mutable reference of StreamNode. However, in some scenarios we only have immutable reference to the stream node, which forces us to unnecessarily take the mutable reference of stream node.

In this PR, we change the visit_stream_node to visit_stream_node_mut, and provide a counterpart method visit_stream_node to only take the immutable reference of stream node.

Besides, the two visit_stream_node_xxx methods are only a special case of visit_stream_node_cont_xxx, which always returns true in the closure passed to visit_stream_node_cont_xxx. Therefore, we change to call the visit_stream_node_cont_xxx in visit_stream_node_xxx instead of implementing by themselves.

Checklist

• I have written necessary rustdoc comments.
• I have added necessary unit tests and integration tests.
• I have added test labels as necessary.
• I have added fuzzing tests or opened an issue to track them.
• My PR contains breaking changes.
• My PR changes performance-critical code, so I will run (micro) benchmarks and present the results.
• My PR contains critical fixes that are necessary to be merged into the latest release.

Documentation

• My PR needs documentation updates.

Release note

[shanicky]

lgtm

[shanicky]

lgtm