Move Layout/LineLength into separate TODO file

What does this MR do and why?

Moves Layout/LineLength into separate TODO file.

Note that although this rule wasn't disabled explicitly before (via Enabled: false) it had a pretty high maximum line length of 1313 which made this rule not complaining at all.

Now that we switch to use the default configuration for maximum line length of 120 we are enabling this cop.

Any files which are not excluded in the here generated TODO YAML will be flagged.

Related to #354328 (closed)

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