Consider adding a `ViValidateAndAcceptLine` function for Vi's command mode

[matteocoder]

Prerequisites

• [X] Write a descriptive title.

Description of the new feature/enhancement

Currently, if the edit mode is set to Vi, ValidateAndAcceptLine works only in insert mode. This new function ViValidateAndAcceptLine could offer the same functionality of the existing function, but in command mode as well.

Proposed technical implementation details (optional)

No response