Fix bug preventing the assist command from working in certain keymaps (#2669)

Fixes: https://github.com/zed-industries/community/issues/1712

The keymaps were adding in a `"cmd-enter": "editor::NewlineBelow",`
entry in the context of `Editor`, and this was clobbering the assist
command in the assistant panel context. Zed now defines this command in
the default keymap under the context of `"context": "Editor && mode ==
full"`. All I needed to basically do was remove that command from the
keymaps. I also removed the `"cmd-shift-enter": "editor::NewlineAbove"
from the `Editor` context in those keymaps as wel, as it is also defined
in the default keymap.

Release Notes:

- Fix bug preventing the `assistant: assist` command from working in
certain keymaps

assets/keymaps/atom.json

@@ -24,9 +24,7 @@
       ],
       "ctrl-shift-down": "editor::AddSelectionBelow",
       "ctrl-shift-up": "editor::AddSelectionAbove",
-      "cmd-shift-backspace": "editor::DeleteToBeginningOfLine",
-      "cmd-shift-enter": "editor::NewlineAbove",
-      "cmd-enter": "editor::NewlineBelow"
+      "cmd-shift-backspace": "editor::DeleteToBeginningOfLine"
     }
   },
   {

assets/keymaps/sublime_text.json

@@ -24,9 +24,7 @@
       "ctrl-.": "editor::GoToHunk",
       "ctrl-,": "editor::GoToPrevHunk",
       "ctrl-backspace": "editor::DeleteToPreviousWordStart",
-      "ctrl-delete": "editor::DeleteToNextWordEnd",
-      "cmd-shift-enter": "editor::NewlineAbove",
-      "cmd-enter": "editor::NewlineBelow"
+      "ctrl-delete": "editor::DeleteToNextWordEnd"
     }
   },
   {

assets/keymaps/textmate.json

@@ -12,8 +12,6 @@
       "ctrl-shift-d": "editor::DuplicateLine",
       "cmd-b": "editor::GoToDefinition",
       "cmd-j": "editor::ScrollCursorCenter",
-      "cmd-alt-enter": "editor::NewlineAbove",
-      "cmd-enter": "editor::NewlineBelow",
       "cmd-shift-l": "editor::SelectLine",
       "cmd-shift-t": "outline::Toggle",
       "alt-backspace": "editor::DeleteToPreviousWordStart",
@@ -56,7 +54,9 @@
   },
   {
     "context": "Editor && mode == full",
-    "bindings": {}
+    "bindings": {
+      "cmd-alt-enter": "editor::NewlineAbove"
+    }
   },
   {
     "context": "BufferSearchBar",