Improve parsing of import suggestions extending multiple multiline imports (fixes #4175)

[jhrcek]

Example ghc error corresponding to test case I'm adding:

Data constructor not in scope: Nothing
Suggested fix:
  Add ‘Nothing’ to one of these import lists:
    ‘Data.Maybe’ (at /home/jhrcek/Tmp/hstest/app/ModuleA.hs:(5,1)-(7,2))
    ‘Prelude’ (at /home/jhrcek/Tmp/hstest/app/ModuleA.hs:(2,1)-(4,2))

[jhrcek]

The original regex didn't correctly deal with import lists spanning multiple lines.
Instead of extracting the whole of

"(/path/to/File.hs:(3,1)-(5,2))"

it would only extract

"(/path/to/File.hs:(3,1)"
                       ^ -only up to first `)`

which led to errors in src span parser described in #4175

[soulomoon]

LGTM. We have some new tests to ensure we fix the bug too. I think it is good fix.

[fendor]

LGTM, only one suggestion.

More tests are always welcome :)

[fendor]

Since this is almost the same, do you think it is a good idea to remove the CPP and use a regex with an optional group like:
"\\((at )?([^:]+:[^ ]+)\\)"

[jhrcek]

Unfortunately this doesn't work, because it introduces a new capturing group in the regex, which changes the number of matches and because of that it fails the check on this line:

haskell-language-server/plugins/hls-refactor-plugin/src/Development/IDE/Plugin/CodeAction.hs

Line 1989 in 97aac54

, let result = if length mods == length srcspans then

I thought I could use non-capturing groups (by adding ?: insite the parens), but then I learned the regex library we're using only supports posix-compliant regex syntax, so this is not supported.
I also remember that java had a way of specifying the index of the capturing group whose match you want to retrieve, but this doesn't seem to be supporter by regex-tdfa.. actually it is supported, but I don't think using more complicated regex functionality (getting capturing group by index) outweighs the benefit of removing one CPP 🤔

[jhrcek]

I'll wait for further suggestions if you have any and will merge it in the afternoon otherwise.