Draft: Refactor(profile/preferences): convert to Vue template

What does this MR do?

This MR is in Draft mode

TODO:

• figure out validation of form submission + flash display
• finalize haml migration of group_overview_selector using an ee_else_ce/-import
• finalize haml migration of integration_views with the following sub-templates:
  • app/views/profiles/preferences/_gitpod.html.haml
  • app/views/profiles/preferences/_sourcegraph.html.haml

Same functionality, but different implementation:

• image lazy load
• checkbox default value
• radio button direct submit (all fields)

Differences to HAML implementation:

• changed select2 to select
• changed quote in "Show one file at a time on merge request’s Changes tab"
• added gl-button class to submit
• changed submit to call submit()

Screenshots

Before:	After:

The new page in action:

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Closes #250846 (closed)