Suppress Unneeded Parenthesizing of Stringized Expressions

[BSalita]

Problem description

Expression stringizer is blindly nesting sub-expressions in parenthesis. Parenthesis should only be added if the sub-expression contains a priority dependent operator.

>>> expr = pl.col("foo") > 2
>>> print(str(expr))
[(col("foo")) > (2i32)]   # should be [col("foo") > 2i32] or (future) [col("foo").gt(2i32)]

[ritchie46]

This requires some state in serialization and to me is something that is not worth our efforts as the extra parentheses are not wrong. If anybody feels this should be addressed, feel free to open a PR.

[BSalita]

Thanks. Exactly.