Make superfluous-parens consider string combinations

[DanielNoord]

Current problem

Although #4784 fixes some problems with superfluous-parens it still does not consider the following cases:

Z = "TestString"
X = ("Test " + "String") # Bad
Y = ("Test " + "String") in Z # Bad
assert "" + ("Version " + "String") in Z # Bad

This is because the current checker focuses on unnecessary parens after keywords (if, else, etc.) and only if the ( immediately follows the keyword. See

if tokens[start + 1].string != "(":
            return

on line 373 in format.py and the fact that we only run when Keywords are present.

Ideally, the checker would also consider string combinations and seeing if parens are necessary there.

Desired solution

Raise superfluous-parens message on the test cases described above.

Additional context

No response

[emmeowzing]

Still seeing this

[clavedeluna]

I'll work on this issue