feat(slider): improve slider variants and gapratio

[lubber-de]

Description

This PR enhances the slider component, so it

• fixes some slider issues
  • tick color on inverted variant
  • tick position on vertical variant
  • wrong gapratio calculation when calculated number of labels is a prime number
  • adds internal caching of otherwise often repeated calculations
• improves labelType "letter" option,
  • which now supports a custom letter string or array (was hardcoded before)
  • "increases" the letters in case more labels than given letters are needed (like the columns of a spreadsheet)
• adds another variant vertical right aligned
• adds an optional value fixed for autoAdjustLabels
• adds another option highlightRange to slightly highlight the selected area range
• supports the usage of ui label

Screenshot

Testcase

https://jsfiddle.net/lubber/1tvumckq/48/

Closes

#3103

[lubber-de]

An enhanced variant of the solution in #3100 is implemented as well by using autoAdjustLabels: 'fixed' as described in #3100 (comment)

[prudho]

Very nice changes ! LGTM 👍