Feature Management Modal improvements (MVC UI)

[hikalkan]

• Checkboxes should be on the left side of the feature name
• Child features should be only selectable when the parent was selected (recursively), just like the permissions.
• Numeric features should properly validate numbers (also in the server) and should show a numeric textbox.
• Test if validators are properly working and fix if not.

These are valid for the SaaS module too.

I am currently writing the Features document: https://github.com/abpframework/abp/blob/rel-3.1/docs/en/Features.md
You can read the document when I complete (tomorrow) and work on this issue then.

[hikalkan]

Documentation is done: https://github.com/abpframework/abp/blob/dev/docs/en/Features.md

[realLiangshiwei]

wait for #5334, #5259 merge

[hikalkan]

@realLiangshiwei they are merged ;)