aliases/vim: simplify code flow

[gaelicWizard]

Description

Simplifies the flow of aliases/vim by short circuiting instead of doing a whole if block and reducing weirds.

Motivation and Context

These were part of my _command_exists branch, but was out of scope.

How Has This Been Tested?

Types of changes

• Bug fix (non-breaking change which fixes an issue)

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.

[cornfeedhobo]

do we want to account for the condition where the user doesn't have vim installed but does have nvim and has aliased that to vim?

[davidpfarrell]

do we want to account for the condition where the user doesn't have vim installed but does have nvim and has aliased that to vim?

I think _command_exists vim will pickup the alias (just confirmed in my local), so I think existing vim logic generally works in this case.

[davidpfarrell]

I don't know if the OS switch was necessarily a bad thing, but I think the _command_exists check will short-circuit out easily enough when not present.

Approved !