Allows use of slightly optimized variants that check if they have to use
the heavier vte parser. Tries to avoid unnnecessary allocations. Initial
performance characteristics proven out in #4378.
Also reduces boilerplate with right-ward drift.
* Test commands for proper names and search terms
Assert that the `Command.name()` is equal to `Signature.name`
Check that search terms are not just substrings of the command name as
they would not help finding the command.
* Clean up search terms
Remove redundant terms that just replicate the command name.
Try to eliminate substring between search terms, clean up where
necessary.
