feat: add tmux-provider plugin (#151)

* feat: add tmux-provider plugin

* fix: invalid thumbnail name

* fix: invalid translation keys

* docs: README updated to include launcher provider entry

Also fixed wording for requirements (validation failed for some reason?)

tmux-provider/translations/en.json

@@ -0,0 +1,15 @@
+{
+  "session_attached": "Attached",
+  "session_detached": "Detached",
+  "tmuxp_config": "tmuxp config",
+  "tmux_not_found": "tmux not found",
+  "tmux_not_found_subtitle": "Install tmux to use this provider",
+  "no_sessions_found": "No sessions found",
+  "no_sessions_subtitle": "Start a tmux session to see it here",
+  "settings": {
+    "use_tmuxp": {
+      "label": "Enable tmuxp",
+      "description": "Also list tmuxp session configurations (via `tmuxp ls`)."
+    }
+  }
+}