feat: Add script-src-elem option to CSP options.

[mark-unwin]

Added a new CSP3 directive for Content Security Policy for script-src-elem.

[mergeable]

Hi there, mark-unwin! 👋

Thank you for sending this PR!

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Sincerely, the mergeable bot 🤖

[neznaika0]

Please do not modify the initial PR template with checkboxes.
You do not need to merge the previous comments from 4.7 - the team will do this.

[michalsn]

Please make sure each pull request only contains commits for its specific change. Commits from other, already merged PRs should not be included.

[github-actions]

👋 Hi, @mark-unwin!

We detected conflicts in your PR against the base branch 🙊
You may want to sync 🔄 your branch with upstream!

Ref: Syncing Your Branch

[paulbalandan]

Please fix the merge conflicts.

[michalsn]

Hey @mark-unwin, are you still interested in this feature? If yes, could you update this PR in the next two weeks?