feat: update to angular 10

[tobiasengelhardt]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/CirclonGroup/angular-tree-component/blob/master/CONTRIBUTING.md#commit-message-guidelines
• Tests for the changes have been added (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

Update to Angular 10, remove old unused packages

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

What is the current behavior?

What is the new behavior?

Does this PR introduce a breaking change?

[x] Yes
[ ] No

Angular v10 is now minimum dependency

Other information