Working on `opt.rst`.
Replace the hardcoded `opt` psuedo code listing with a `literalinclude` from `/cmd/opt.rst`.
Reorder and update `opt_*` list to match current `opt`.
Expand sub-section titles with the function of the pass (keeping the `:cmd:ref:` part at the end to prevent the Esbonio error in vscode when a heading starts with a directive).
Move comments about `clean` and `;;` being aliases into final `opt` subsection.
Also renames `Test suites` -> `Testing Yosys`.
9fe3dcda78