Don't allocate to compare string slices

[martin-g]

Which issue does this PR close?

• Closes #.

Rationale for this change

Replace usages of str::to_lowercase().as_str() + patterm matching with str::eq_ignore_ascii_case(&str) to avoid allocating temporary String.

What changes are included in this PR?

It is a boring change from

match some_str.to_lowercase().as_str() {
 "one" => ...,
 "two" => ...,
 ...
}

to

if some_str.eq_ignore_ascii_case("one") { 
  ...
} else if some_str.eq_ignore_ascii_case("two") {
  ...
} ...

Are these changes tested?

The logic should be already covered by old tests.

Are there any user-facing changes?

No.

[martin-g]

There are many more occurrences of this pattern in the code base.

I updated just a few to see whether the change would be accepted. Maybe the gain is not big enough and the code style is not preferred.