Add line endings indicator in status bar

[kitt-cat]

Closes #5294

This PR adds a line ending indicator to the status bar, hidden by default as discussed in #5294.

Changes

• 8b063a2 add the indicator and status_bar.line_endings_button setting.

• 9926237 changes status_bar.line_endings_button from a boolean to an enum:

  show details

  • always Always show line endings indicator.
  • non_native Indicate when line endings do not match the current platform.
  • lf_only Indicate when using unix-style (LF) line endings only.
  • crlf_only Indicate when using windows-style (CRLF) line endings only.
  • never Do not show line endings indicator.

  I know this many options might be overdoing it, but I was torn between the pleasant default of non_native and the simplicity of lf_only / crlf_only.

  My thinking was if one is developing on a project which exclusively uses one line-ending style or the other, it would be nice to be able to configure no-indicator-in-the-happy-case behavior regardless of the platform zed is running on. But I'm not really familiar with any projects that use exclusively CRLF line endings in practice. Is this a scenario worth supporting or just something I dreamed up?

• 0117419 rename the action context for line ending: Toggle -> line ending selector: Toggle.
  When running the action in the command palette with the old name I felt surprised to be greeted with an additional menu, with the new name it feels more predictable (plus now it matches language_selector::Toggle!)

Future work

Hidden status bar items still get padding, creating inconsistent spacing (and it kind of stands out where I placed the line-endings button):

I started a new follow-up PR to address that: #39992

Release Notes:

• Added line ending indicator to the status bar (disabled by default; enabled by setting status_bar.line_endings_button to true)

[semioticrobotic]

Amazing. Thank you so much for this, @kitt-cat.

[ConradIrwin]

@kitt-cat nice!

• I think the padding is due to the invisible status item about language_toolchain between the two existing items. I think we can fix that by adding a new method to the settings trait is_visible() and filtering the invisible ones out here:

  zed/crates/workspace/src/status_bar.rs

  Line 79 in 3707102

  .children(self.right_items.iter().rev().map(|item| item.to_any()))

• I think we should stick with true/false for now (although I'm also excited by the idea of "it shows up when you need it", it seems unnecessarily fiddly – how do we know whether a file is expected to have "\r\n" or "\n"? And then when you change the line ending the UI disappears on you, which is a bit weird?).
• Change to the action name seems reasonable (makes it more consistent)

[ConradIrwin]

We could maybe try downcasting the element returned by render, but it's probably clearer overall to make the logic explicit.

For ones that aren't causing problems (i.e. anything except the language toolchain selector) it seems fine to leave is_visible as true?

[zed-industries-bot]

	Messages
📖	This PR includes links to the following GitHub Issues: #5294 If this PR aims to close an issue, please include a Closes #ISSUE line at the top of the PR body.

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[kitt-cat]

Hello again, I moved the spacing related changes in a new PR (#39992) to manage scope creep, if that is ok!

I hope this PR may be merge-ready now, is there anything more you'd like to see?

[ConradIrwin]

Thanks again for this!