add customizable read-only indicator to statusbar

[sbromberger]

closes #2627.

[sbromberger]

Would it be possible to get this reviewed soon? Merging will require me to modify #2831 but this lays the groundwork for these sorts of changes.

[the-mikedavis]

If anything, we may want to wait on this for #2434 and then split out the helix_view::editor::StatusLineElement::FileName component into separate elements for the modification and read-only indicators.

Whether to default this to being enabled or disabled is worth some discussion: kakoune does not show a read-only indicator but vim does.

[sbromberger]

kakoune does not show a read-only indicator but vim does.

The problem we currently have with helix is that it's possible to lose work because of the lack of realization that you're editing a RO file.

[the-mikedavis]

That particular issue was fixed recently: #1575

[sbromberger]

That particular issue was fixed recently: #1575

Wow, I didn't even see that merged. Thanks!

[sbromberger]

Turns out this was more straightforward than I had expected (thanks to the great new statusline implementation). This works for me locally but more review would be appreciated.

[the-mikedavis]

This is looking good to me. I think enabling this by default is a good choice 👍

[dead10ck]

@the-mikedavis is there anything else this PR needs?

[the-mikedavis]

The bufferline commits should probably be dropped out of the changes but otherwise this looks good to me