Slider labels feature

[Aleksandyr]

Closes #3449
Closes #4562
Closes #4559
Closes #2622

Additional information (check all that apply):

• Bug fix
• New functionality
• Documentation
• Demos
• CI/CD

Checklist:

• All relevant tags have been applied to this PR
• This PR includes unit tests covering all the new code
• This PR includes API docs for newly added methods/properties
• This PR includes feature/README.MD updates for the feature docs
• This PR includes general feature table updates in the root README.MD
• This PR includes CHANGELOG.MD updates for newly added functionality
• This PR contains breaking changes
• This PR includes ng update migrations for the breaking changes
• This PR includes behavioral changes and the feature specification has been updated with them

[Aleksandyr]

This PR needs further updates related to the thumb labels, due providing users with ability to implement custom templates representing those labels. The main goal for exposing them was to allow users cut off the text that the label contains. As we've already discussed with @simeonoff, below are the changes that need to be added.

%igx-thumb-label {
        max-width: rem(80px);
        overflow: hidden;
}

[Aleksandyr]

@simeonoff has updated the slider sample in order to show how the user can manipulate the label in order to fit the text within the thumbs.

[zdrawku]

@Aleksandyr update che changelog as well

[nrobakova]

I tested this PR and found some issues:

1. When slider type is Range and move with the key board the next trump is not previewed, and if I move over it and continue navigation it does not hides
2. When change slider type from Slider to Range, the first trump cannot be moved
3. When remove labels for a slider, then add new with 2 items and then add again labels with 6 items the max value of the slider becomes 1

[Aleksandyr]

API documentation should be updated.