Docs: static opt macro list

Also adds `docs/tests/macro_commands.py` which checks all commands in
`code_examples/macro_commands` against the current yosys build. Format similar
to `run-test.sh` files: logging the file under test and reporting errors.

docs/source/code_examples/macro_commands/opt.ys

@@ -0,0 +1,14 @@
+#start: passes in the following order:
+#end: When called with -fast
+opt_expr
+opt_merge -nomux
+
+do
+    opt_muxtree
+    opt_reduce
+    opt_merge
+    opt_share  (-full only)
+    opt_dff  (except when called with -noff)
+    opt_clean
+    opt_expr
+while <changed design>