[`flake8-comprehensions`] Handle template strings for comprehension fixes (#18710)
Essentially this PR ensures that when we do fixes like this:
```diff
- t"{set(f(x) for x in foo)}"
+ t"{ {f(x) for x in foo} }"
```
we are correctly adding whitespace around the braces.
This logic is already in place for f-strings and just needed to be
generalized to interpolated strings.