Relates to #4324 (but slightly orthogonal.)
We wanted some message classes to be handled in the lexical model editor
more cleanly, including drill-down to line of error. A few changes
required to make this work well:
1. Parse error messages from kmlmc. This is not perfect but works while
the two projects are kept in sync, which they always are for Keyman
Developer. Note that at this stage, .ts warnings are not captured in
this parser, as they are generated by tsc.
2. Drill-down in Wordlist Editor Frame to find line of error
3. Model editor reports ownership of .tsv files so they can be loaded
4. In case of model editor not open (e.g. building from project view),
the TSV standalone editor was not displaying the frame, so it never
actually worked.
5. If the text editor had never loaded, then FindError was effectively
a no-op; adds code to seek to error line after page load finishes.
6. Ensures that if we attempt to seek an error in a sub-file owned by
an editor (e.g. .tsv owned by .model.ts, .kvks owned by .kmn), that
the parent editor will be focused first. Does not verify all paths
here, just the tsv one.
