Channel switcher UI improvements (#6564)

* Channel switcher UI improvements

* Reverting mattermost theme

* Fixing spacing above the button

* Updating switcher button

* PLT-6691 - Fixing tablet header

webapp/i18n/en.json

@@ -1173,10 +1173,10 @@
   "quick_switch_modal.help_no_team": "Type a channel name. Use ↑↓ to browse, ↵ to confirm, ESC to dismiss",
   "quick_switch_modal.channels": "Channels",
   "quick_switch_modal.teams": "Teams",
-  "quick_switch_modal.teamsShortcut.mac": "(CMD+ALT+K)",
-  "quick_switch_modal.teamsShortcut.windows": "(CTRL+ALT+K)",
-  "quick_switch_modal.channelsShortcut.mac": "(CMD+K)",
-  "quick_switch_modal.channelsShortcut.windows": "(CTRL+K)",
+  "quick_switch_modal.teamsShortcut.mac": "- ⌘⌥K",
+  "quick_switch_modal.teamsShortcut.windows": "- CTRL+ALT+K",
+  "quick_switch_modal.channelsShortcut.mac": "- ⌘K",
+  "quick_switch_modal.channelsShortcut.windows": "- CTRL+K",
   "channel_switch_modal.not_found": "No matches found.",
   "channel_switch_modal.submit": "Switch",
   "channel_switch_modal.title": "Switch Channels",
@@ -1974,8 +1974,6 @@
   "sidebar.moreElips": "More...",
   "sidebar.otherMembers": "Outside this team",
   "sidebar.pg": "Private Channels",
-  "sidebar.switch_channels": "Switch Channels (CTRL + K)",
-  "sidebar.switch_channels.mac": "Switch Channels (CMD + K)",
   "sidebar.removeList": "Remove from list",
   "sidebar.tutorialScreen1": "<h4>Channels</h4><p><strong>Channels</strong> organize conversations across different topics. They’re open to everyone on your team. To send private communications use <strong>Direct Messages</strong> for a single person or <strong>Private Channel</strong> for multiple people.</p>",
   "sidebar.tutorialScreen2": "<h4>\"{townsquare}\" and \"{offtopic}\" channels</h4><p>Here are two public channels to start:</p><p><strong>{townsquare}</strong> is a place for team-wide communication. Everyone in your team is a member of this channel.</p><p><strong>{offtopic}</strong> is a place for fun and humor outside of work-related channels. You and your team can decide what other channels to create.</p>",