feat(fmt): add sort_imports config

[meetmangukiya]

Motivation

Sorting imports is a desirable feature.
Closes #3396. I didn't check the issues first and went head first into the implementation because I wanted import sorts but see now that @rkrasiuk is already assigned to the issue 😅 .

Solution

Sorts the SourceUnitPart::Import parts before running it through the formatter. Sort works but blanks and slicing need to be fixed. Also, as I built this I have realized few things:

1. Contiguous imports detection based off just contiguous SourceUnitPart::Import wont be correct because blank lines do not have a SourceUnit entry. Need to use self.blank_lines somewhere to better determine the slice boundaries.
2. Currently, it uses blank_lines to determine if there should be a space between formatted units, need to fix it. I am thinking maybe there is a way to use the needs_space callback in conjunction with the import_slices to determine the blank spaces to add correctly.

Opening a WIP PR, because it might not be the best or even a correct way to do this.

[Evalir]

hey @meetmangukiya i think this is good! do you plan on finishing this, or should we take over?

[meetmangukiya]

Will get back to this when I find time. In the mean time if you want to take over it's also fine.

[meetmangukiya]

I also am interested in a feature for sorting functions by receive, fallback, visibility, mutability, payable, etc. as here. Which I think could be done similarly? Maybe could reuse some parts from here too.

[aviggiano]

Hello

This is a great feature.
Would it be possible to also include "remove unused imports" in the PR?

[mattsse]

I completed this by taking the original approach and merely modifying the group detection.

This currently only sorts individual import groups (separated by newline) and does not reorder groups. I guess we could reorder groups as well but this should be a separate setting.

there's a limitation when a group contains a comment, but we can live with that for now.
perhaps there are other edge cases but since this is opt-in, this should be good for now until they get reported.

[meetmangukiya]

🐐