languages: Fix Bash indentation issues with multi-cursors, newlines, and keyword outdenting (#35116)

Closes #34390

This PR fixes several Bash indentation issues:

- Adding indentation or comment using multi cursors no longer breaks
relative indentation
- Adding newline now places the cursor at the correct indent
- Typing a valid keyword triggers context-aware auto outdent

It also adds tests for all of them.

Release Notes:

- Fixed various issues with handling indentation in Bash.

Cargo.lock

@@ -4979,6 +4979,7 @@ dependencies = [
  "text",
  "theme",
  "time",
+ "tree-sitter-bash",
  "tree-sitter-html",
  "tree-sitter-python",
  "tree-sitter-rust",