[vi-mode] Supports 'diw' text-object command.

[springcomp]

PR Summary

Fixes #2057.

This PR is a first attempt at supporting text-objects in vi-mode. It includes a reasonably complete implementation of the diw command.

Although I have worked hard to make this PR production ready, it must still be considered WIP. I would really appreciate feedback about the implementation.

If this is deemed interesting enough, it could be the first step towards a much complete set of pull requests as alluded to in #584.

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Make sure you've added one or more new tests
• Make sure you've tested these changes in terminals that PowerShell is commonly used in (i.e. conhost.exe, Windows Terminal, Visual Studio Code Integrated Terminal, etc.)
• User-facing changes
  • Documentation needed at PowerShell-Docs
    • Doc Issue filed: pending feedback

Microsoft Reviewers: Open in CodeFlow

[daxian-dbw]

@springcomp I resolved the conflicts. Will finish the review tonight.

[daxian-dbw]

LGTM

[sharpchen]

Can we have it exposed to [Microsoft.PowerShell.PSConsoleReadLine] class? I tried to remap this to another chord but failed to find a work around

[springcomp]

Can we have it exposed to [Microsoft.PowerShell.PSConsoleReadLine] class? I tried to remap this to another chord but failed to find a work around

Unfortunately, that PR has been merged a bit too quickly.
The current handler is not a public method that can be remapped, unfortunately.

I addressed feedback from follow up conversations in a future pull request that addresses this shortcomings.