[Fix #7826] Add new Layout/SpaceAroundMethodCall cop

[saurabhmaurya15]

This MR adds a cop to for checking dot method calls to not have spaces around them.
It works for multiple method calls in a single line or in multiple lines.

closes #7826

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Before submitting the PR make sure the following are checked:

• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Added an entry to the Changelog if the new code introduces user-observable changes. See changelog entry format.
• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Run bundle exec rake default. It executes all tests and RuboCop for itself, and generates the documentation.

[rrosenblum]

Should this support auto-correction? How does this work with safe navigation?

[bbatsov]

I think this cop should be a bit broader and check for all method invocation operators - @rrosenblum already mentioned safe navigation, but there's also ::. Probably the name should be something like "SpaceAroundMethodCallOperator" or something like this.

[bbatsov]

You can also have chaining in a suffix form.

[saurabhmaurya15]

Chaining in a suffix form is a bad style. There is already a cop for that so not including it in the example.
I have added a spec for chaining in suffix form though.

[bbatsov]

I'd use "method call operator" terminology here.

[saurabhmaurya15]

Makes sense. Changing it to Checks method call operators to not have spaces around them.
Keeping it plural since it can have method chains also.

[saurabhmaurya15]

@bbatsov I have changed name to SpaceAroundMethodCallOperator. I'll add checks for safe navigation operator and :: too.

[bbatsov]

Okay, ping me when this is ready for a review again.

[saurabhmaurya15]

@bbatsov This is ready for review.

[bbatsov]

@saurabhmaurya15 I think you can improve the test suite a bit if you used shared examples there, as the tests for ., :: and .& are mostly the same. Apart from this - it seems to me we're pretty close to finishing the cop.

[bbatsov]

Thanks!