Improve clicking in diff view to enter staging/patch building

[stefanhaller]

When using delta with the --hyperlinks --hyperlinks-file-link-format="lazygit-edit://{path}:{line}" option, you can now click on a line that has an underlined line number, and it will take you straight to the staging panel (when you're in the files panel) or the patch building panel (when you're looking at a commit). Previously this was already possible when a single file was selected in the files panel; but it didn't work when a directory was selected, or when looking at the diff of a commit.

See #3986 for more information.

The implementation is a very rough proof of concept only; don't review the code (yet).

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
Report missing for a22aced1	✅ 44.86%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (a22aced)	Report Missing	Report Missing	Report Missing
Head commit (075b5fa)	58796	51049	86.82%

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#3985)	292	131	44.86%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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Footnotes

1. Codacy didn't receive coverage data for the commit, or there was an error processing the received data. Check your integration for errors and validate that your coverage setup is correct. ↩

[stefanhaller]

One things that's a little strange is that when looking at the diff of a commit, it takes one click (or enter keypress) to go to patch building, but then it takes two escape presses to get out again. It's weird and takes some getting used to, but I think it's a good price to pay because the feature is so useful. If it bothers us too much we can consider remembering where we came from, and have esc take you all the way out to commits in that case (which may also be confusing though).

[stefanhaller]

If it bothers us too much we can consider remembering where we came from, and have esc take you all the way out to commits in that case

I added a commit that does this, I think I prefer it this way (needs more testing though).