Implement design for start button

See merge request new-vector/modular/chatterbox!5

Users can specify explicitly what name, avatar they want to use in the
config

Fix UI not sticking in place

See merge request new-vector/modular/chatterbox!4

Namespace CONFIG_LOCATION to CHATTERBOX_CONFIG_LOCATION

See merge request new-vector/modular/chatterbox!1

Use git-lab ci to do automatic build and release on tag creation

See merge request new-vector/modular/chatterbox!3

- This will copy it to /target during build
- config.json will also be served from root with the dev server

- No need for this now that we're using the sdk as a package

One to produce the chatterbox app and the other to output the script and
resources needed for parent.