Allow command name resolution for GHCi commands with option `!`

Motivation

Currently, GHCi can't perform command name resolution with option ! as follows:

ghci> :k Int
Int :: *

ghci> :k! Int
unknown command ':k!'
use :? for help.

However, :kind! command is useful, especially in recnet kind-rich GHC.

Proposal

So I propose change to the prefix match implementation of GHCi as follows:

Current implementation:

• Prefix match with full string including the option ! (e.g. k!)

Proposed implementation:

• Prefix match without option suffix ! (e.g. k)
• in addition, suffix match with option !

I have a patch for this. I'll send MR.

See also #8305 (closed) and #8113 (closed)