PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/tools/notes/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
• You have signed the CLA.
• All existing tests are passing: https://github.com/NativeScript/NativeScript/blob/master/tools/notes/DevelopmentWorkflow.md#running-unit-tests-application.
• Tests for the changes are included - https://github.com/NativeScript/NativeScript/blob/master/tools/notes/WritingUnitTests.md.

What is the new behavior?

This PR performs some refactoring on the style-properties module.
More specifically:

• Added new FixedLengthType type. It's only used for translate css properties but can cover more needs in the future
• Corrected a few transform types in animation module
• Added ClipPathFunction class. This class will keep data related to clip-path shape functions
• Moved all transform-related functions from style-properties to a new css-transform module
• Removed any type casts and improved types in css-transform module
• Moved all style-properties functions to the top
• Removed duplicate code used for calculating shorthand css properties
• Added value converter and equality comparer for clip-path property