Imrpove performance by limitting on_send calls

[Darhazer]

I noticed that Rubocop, since v0.90, has an optimization for not calling on_send based on the expected method_name for the cop.

I applied that to the cops for it was easy (which is about 50% of the cops). Due to the configurable language, it might be hard to do for some cops, and for others, it just requires more refactoring, as the cops check for a method somewhere down the chain.

I haven't really measured the performance improvement, but a naive test (running it with time over our own specs) shows a significant difference.

cc: @fatkodima

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• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Updated documentation.
• Added an entry to the CHANGELOG.md if the new code introduces user-observable changes.
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[fatkodima]

👍 Yeah, this definitely should make a noticeable difference.

[marcandre]

Perfect!
It's always faster to use RESTRICT_ON_SEND whenever possible, no need to benchmark it 👍
Thanks!