feat: refactor & upgrade to Angular 16, main dependencies (no RxDB upgrade yet)

[voznik]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/voznik/ngx-odm/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[x] Code style update (formatting, local variables)
[x] Refactoring (no functional changes, no api changes)
[x] Build related changes
[x] CI related changes
[x] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

• upgrade to Angular 16
• upgrade main dependencies (no RxDB upgrade yet)
• refactor - rename files & introduce library secondary entry points, move to config, collection, core, utils, testing
• refactor collection service:
  • init in constructor
  • move wait for init observable to method decorator, also call original method w\o subscribe
  • introduce public count method, called via common static collection method
• fix & refactor example (demo) TodoMVC application - fix footer, edit todo, clear completed todos
• fix README docs

Does this PR introduce a breaking change?

[x] Yes
[ ] No

Other information