new rule - useless if statement/expression

[DetachHead]

ruff should be able to detect if the code on both sides of an if statement are identical, and report it as unnecessary

if 1: # error: both sides of the if statement are the same
    print(1)
else:
    print(1)

asdf = 1 if bool() else 1 # error: both sides of the if expression are the same

[sanxiyn]

This is similar to if-with-same-arms (SIM114) in flake8-simplify, so I filed a rule request upstream: MartinThoma/flake8-simplify#192.