Refactor several javascript files to ES module syntax

Follow up to !12581 (merged) which removes unnecessary globals and refactors scripts that rely on them into proper ES module exports.

Part of #33391 (closed) and #20983 (moved)

Note to reviewer: please don't squash this MR. If for some reason any of these changes need to be rolled back, I'd prefer to be able to roll the commits back independently rather than reverting the entire MR.

added 2 commits

• 571de11e - refactor Todos class to ES module syntax
• d990df74 - refactor TaskList class to ES module syntax

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added 1 commit

• a23db42e - refactor Star class to ES module syntax

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added 1 commit

• a23db42e - refactor Star class to ES module syntax

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added 1 commit

• 5c52ca9a - refactor SingleFileDiff class to ES module syntax

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added 1 commit

• 60a1118f - refactor SigninTabsMemoizer class to ES module syntax

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resolved all discussions

I've verified that this merges cleanly into EE master once a few other commits make it in the next ce-to-ee merge.

@timzallmann can you review/merge?

assigned to @timzallmann

Restructuring looks good, only issue are those tests

assigned to @mikegreiling

resolved all discussions

approved this merge request

merged

mentioned in commit c88739ff

changed milestone to %9.4

assigned to @timzallmann

mentioned in issue #37952