This is a prerequisite to fix a bug in template completions whereby
completion of the string `ti` for the variable `title` results in
`tititle`.
This is because the position where the completion is requested is used
to insert the completion text. This is incorrect. Instead, a
`replacementSpan` should be used to indicate the span of text that needs
to be replaced. Angular's own `Completion` interface is insufficient to
hold this information. Instead, we should just use ts.CompletionEntry.
Also added string enum for `CompletionKind`, which is similar to
ts.ScriptElementKind but contains more info about HTML entities.
PR Close#32375
f6e88cd659