[RSZ] Add a fully rebuffer command.

[Logikable]

No description provided.

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[gemini-code-assist]

Code Review

This pull request introduces a new fully_rebuffer command, which is exposed through Tcl. The implementation involves adding the command definition in Tcl, a SWIG interface function, and presumably a C++ implementation (not shown in the diff). The documentation in the README has also been updated. My review focuses on the clarity and correctness of the added code and documentation. I've suggested a minor improvement to the README for clarity and to fix a typo, noting that the comment refers to the command on the following lines.

[gemini-code-assist]

There appears to be a typo ('resteinering') and the phrasing could be clearer. Using 're-Steiner-ing' would be more accurate if a Steiner tree algorithm is used. Also, 'positive slack' is more standard terminology than 'leeway in their slack'. Note that the comment refers to the command on the following lines.

Suggested change

	This command goes through each driver pin, stripping all buffers then resteinering
	the pin's buffer tree, before attempting to recover some area for pins that have leeway in
	their slack.
	This command goes through each driver pin, stripping all buffers then re-Steiner-ing
	the pin's buffer tree. It then attempts to recover area for pins that have
	positive slack.

References

1. In shell scripts or command examples, a comment on its own line often refers to the command on the next line, not the one preceding it.