Cleaned some completion files and using _command_exists helper function

[tbhaxor]

Description

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• If my change requires a change to the documentation, I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• If I have added a new file, I also added it to clean_files.txt and formatted it using lint_clean_files.sh.
• I have added tests to cover my changes, and all the new and existing tests pass.

[NoahGorny]

Hey @tbhaxor, I am impressed by the effort you have put in this PR. I suggest, for the ease of checking this, that you split this PR to one completion file at a time. This will help us review and merge it faster. You already did good by splitting the changes between commits, so it should not be so difficult.
Thank you for doing this!

[tbhaxor]

@NoahGorny Since this PR for one specific change that's why I have created one PR.

If you still want file / PR, I will do it from next time

[NoahGorny]

@NoahGorny Since this PR for one specific change that's why I have created one PR.

If you still want file / PR, I will do it from next time

Its just very hard to CR, if you dont want, I can open them up myself

[tbhaxor]

@NoahGorny Since this PR for one specific change that's why I have created one PR.
If you still want file / PR, I will do it from next time

Its just very hard to CR, if you dont want, I can open them up myself

I would so thankful. BTW, what's CR?

[NoahGorny]

@NoahGorny Since this PR for one specific change that's why I have created one PR.
If you still want file / PR, I will do it from next time

Its just very hard to CR, if you dont want, I can open them up myself

I would so thankful. BTW, what's CR?

CR- Code Review, as in reviewing the code and deciding if it's ready or not 😄

[NoahGorny]

@NoahGorny Since this PR for one specific change that's why I have created one PR.

If you still want file / PR, I will do it from next time

I have split this PR into many separate pieces, ignoring removal commits or commits that touch code that we copied from somewhere. you are welcome to take a look @tbhaxor

Closing this as we will continue in those PRs