This commit introduces a new API for the `TemplateTypeChecker` which allows
for autocompletion in a global expression context (for example, in a new
interpolation expression such as `{{|}}`). This API returns instances of the
type `GlobalCompletion`, which can represent either a completion result from
the template's component context or a declaration such as a local reference
or template variable. The Language Service will use this API to implement
autocompletion within templates.
PR Close#39048
f2fca6d58e