Fix manual_range_contains false negative with chains of && and ||

[evantypanski]

Fixes #8745

Since the precedence for && is the same as itself the HIR for a chain of && ends up with a right skewed tree like:

     &&
    /  \
  &&   c2
 /  \
... c1

So only the leftmost && was actually "fully" checked, the top level was just c2 and && so the manual_range_contains lint won't apply. This change makes it also check c2 with c1.

There's a bit of a hacky solution in the second commit to check if the number of open/closing parens in the snippet match. This is to prevent a case like ((x % 2 == 0) || (x < 0)) || (x >= 10) from offering a suggestion like ((x % 2 == 0) || !(0..10).contains(&x) which now won't compile.

Any suggestions for that paren hack welcome, kinda new to working on this so not too sure about possible solutions :) it's weird because I don't know how else to check for parens in HIR considering they're removed when lowering AST.

changelog: Fix [manual_range_contains] false negative with chains of && and ||

[rust-highfive]

r? @Manishearth

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[Manishearth]

@bors r+

[bors]

📌 Commit 257f097 has been approved by Manishearth

[bors]

⌛ Testing commit 257f097 with merge 5b1a4c0...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: Manishearth
Pushing 5b1a4c0 to master...