Do not mix default config with user config in var/themes/default.

[dmarteau]

This is a follow up for 3liz/lizmap-docker-compose#25

Is your feature request related to a problem? Please describe

ATM the docker configuration for lizmap is a kind of a mess and user configuration is mixed with default config wich require to mount a lot of volumes of what should stay private on the host.

Il seems it is not actually possible to use custom configuration for theme with docker because required default files are located at the same location required for the user configuration.

Describe the solution you'd like

It should be possible to place user theme configuration in another location than the default config files

[laurentj]

Since Lizmap 3.6, there is no more static files in var/, to this issue is fixed