Simplify `a AND a` and `a OR a`.

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
Some features like #3859 may find / introduce seemingly nonsensical predicates like a AND a -- in this case the expression simplifier should remove them.

Describe the solution you'd like
Add rewrite rules to rewrite
a AND a --> a
a OR a --> a

Rewrite rules are https://github.com/apache/arrow-datafusion/blob/feff5dc/datafusion/optimizer/src/simplify_expressions.rs#L793

[alamb]

Marking as good first issue as there are many examples and existing tests to follow

[retikulum]

I will take a look!

[alamb]

As pointed out by @src255 this is already implemented #3915 (comment) 🤔