LSP: provide some template expansion features

[hzeller]

The emacs verilog mode ( https://www.veripool.org/verilog-mode/ ) has some neat features to expand templates right inside the editor.

The langauge server can emply CodeAction features to offer modifying the code in the editor, so can be made to provide similar features as well.

From users, we got requests to implement a few basic features that behave similar to the emacs mode correspondence. If they are integrated in the language server, they will work not only in emacs, but all other editors that support the language server (from vim to vscode).

An initial survey [^1] showed these to be the first level of important template operations

• AUTOINST
• AUTO_TEMPLATE
• AUTOINPUT, AUTOOUTPUT, AUTOWIRE

[^1]: sed 's/.*\(AUTO[A-Z_]*\).*/\1/p;d' *.sv | sort | uniq -c | sort -rn

[kbieganski]

• [x] AUTOARG (first attempt at AUTOs) #1579
• [x] AUTOINST with AUTO_TEMPLATE #1617
• [x] AUTO_TEMPLATE special [] syntax #1719
• [ ] AUTO_TEMPLATE module name regex with substitution (@) #1818
• [ ] AUTO_TEMPLATE port connection regex with substitution #1818
• [x] AUTOINPUT, AUTOOUTPUT, AUTOINOUT #1691
• [x] AUTOWIRE, AUTOREG #1691
• [x] signal dimension propagation in AUTO expansion #1719