refactor: rename file_tree and simplify naming

This makes the file tree palette match the other palettes a little better.

src/keybind/builtin/emacs.json

@@ -6,7 +6,7 @@
             ["ctrl+=", "adjust_fontsize", 1.0],
             ["ctrl+-", "adjust_fontsize", -1.0],
             ["ctrl+r", "find_file"],
-            ["ctrl+x d", "open_project_file_tree"],
+            ["ctrl+x d", "open_file_tree"],
             ["ctrl+h ctrl+a", "open_help"],
             ["ctrl+c ctrl+o", "open_recent_project"],
             ["ctrl+c g", "find_in_files"],

src/keybind/builtin/flow.json

@@ -28,7 +28,7 @@
             ["ctrl+w", "close_split"],
             ["ctrl+o", "open_file"],
             ["ctrl+e", "open_recent"],
-            ["ctrl+shift+e", "open_project_file_tree"],
+            ["ctrl+shift+e", "open_file_tree"],
             ["alt+o", "open_previous_file"],
             ["ctrl+shift+t", "restore_closed_tab"],
             ["ctrl+shift+f5", "reload_file"],

src/keybind/builtin/helix.json

@@ -220,7 +220,7 @@
             ["page_down", "move_scroll_page_down"],
 
             ["space F", "find_file"],
-            ["space e", "open_project_file_tree"],
+            ["space e", "open_file_tree"],
             ["space S", "workspace_symbol_picker"],
             ["space D", "workspace_diagnostics_picker"],
             ["space P", "system_paste"],