Replace the save button with the button component with a loading state viarant

[jldec]

The initial Beta implementation (PR #7337) of Dotfiles support uses a simple text input for users to configure the URL of their dotfiles repository.

This issue defines a repo-selection UI to make this process more friendly by allowing users to search for and select their dotfiles repo without leaving the dashboard.

Proposed specifiication

• Select any repo under your personal account (users must clone first if they want to use a 3rd-party dotfiles repo).
• Choose from repos from any existing git provider integration.
• Don't offer to add new git provider integrations inside the repo selection flow, instead link to the main integrations setttings page (leaving the flow).

[PatMyron]

Would love it to default if a repo is named dotfiles:
#7337 (comment)