chore: Codespace Improvements (#4867)

- switch to ubuntu base image
- use rbenv to manage ruby 
- add gh to base image

.devcontainer/Dockerfile

@@ -5,4 +5,4 @@ FROM ghcr.io/chatwoot/chatwoot_codespace:latest
 # Do the set up required for chatwoot app 
 WORKDIR /workspace
 COPY . /workspace
-RUN yarn && gem install bundler && bundle install 
+RUN yarn && gem install bundler && bundle install