Remove the `blocklyNonSelectable` CSS class and include non-selectability in existing classes instead

[BeksOmega]

The blocklyNonSelectable class just disables user selection. Instead of having a CSS class that is used to apply one CSS rule, we should include the rule in a more relevant class.

[dakshkanaujia]

Hey! @BeksOmega, please assign me this issue, I am working on it!

[BeksOmega]

Hiya @dakshkanaujia Go for it! Let me know if you have any questions =)

[dakshkanaujia]

Hey @BeksOmega, I can see the issue. The blocklyNonSelectable class is redundant. I can implement the functionality directly in the existing class. Am I on the right track?

[BeksOmega]

Yes! You want to move user-select: none into other CSS classes that are also defined on the DOM element.

[dakshkanaujia]

Hey @BeksOmega , can you help me with how can I proceed from here , to get this PR merged. I am facing issue in signing the CLA thing.