Sm/remote-tracking-no-config-file

[mshanemc]

What does this PR do?

Don't use ConfigFile
Preserve file format, but in-memory uses Map
Remove unused public methods (this module is NOT exported from STL so it's not a public API anyway, no breaking changes to be concerned about)

What issues does this PR fix or reference?

@W-14399468@

[shetzel]

QA Notes (using dreamhouse-lwc project). All actions below were as expected so a global ✅

1. create a scratch org and project deploy preview
2. project retrieve preview
3. project deploy start
4. project deploy preview
5. make remote change and project retrieve preview
6. project retrieve start
7. make local change and project deploy preview
8. project deploy start
9. make local and remote change to same metadata and project deploy preview and project retrieve preview
10. project deploy start --ignore-conflicts
11. project deploy preview and project retrieve preview

create a new project (sf project generate), auth to the scratch org used above, then
12. project retrieve preview
13. project retrieve start pulls all the source
14. project retrieve preview

[shetzel]

Also ran
project reset tracking and project delete tracking and both behaved as expected.