The existing violations of the @gitlab/no-runtime-template-compiler rule
fall into a few different categories:

- True violations
  - Explicit `template` options in Vue component definitions
  - Implicit violations by relying on the mounting element to contain
    the template, generated by the backend
- False violations
  - Instantiating a Vue SFC by spreading it into `new Vue`, e.g.:
    `new Vue({ el, ...SomeVueSFC });`
  - EE components which use `extends` of a CE component, which itself
    correctly uses an ahead-of-time compiled template
  - Pretty much any file that defines a global Vue mixin

The more straight-forward true violations have been fixed and verified
as working, although there doesn't seem to be existing unit tests for
them.

The aren't many examples of false violations in the codebase, though
it's feasible that the lint rule could be improved to not report these
in future.

The rule is disabled entirely for specs, since in that context, having
a runtime template compiler can be useful.

Addresses https://gitlab.com/gitlab-org/frontend/eslint-plugin/-/issues/24,
part of https://gitlab.com/groups/gitlab-org/-/epics/5142.