Refactor webserver proxy variables and fix BigBlueButton deployment behavior

Refactor proxy/webserver configuration variables to a consistent webserver_* naming scheme across roles. Replace legacy variables like proxy_extra_configuration, client_max_body_size, vhost_flavour, location_ws and ws_port with webserver_extra_configuration, webserver_client_max_body_size, webserver_vhost_flavour, webserver_websocket_location and webserver_websocket_port. Update NGINX vhost and location templates (html, upload, ws, basic, ws_generic) as well as callers (sys-front-inj-all, sys-stk-front-proxy, various web-app-* and web-svc-* roles) to use the new naming.

Tighten docker-compose Git repository handling by making docker_git_repository_pull depend on docker_git_repository_address being defined, a string and non-empty. This avoids accidental Git operations when the repository address is unset or of the wrong type.

Refactor the BigBlueButton role structure and fix deployment bugs: introduce 01_core.yml to orchestrate docker/proxy setup, database seeding, websocket map deployment, docker-compose overrides and admin/bootstrap logic in a single once-executed entrypoint. Rename supporting task files (02_docker-compose.yml, 03_administrator.yml, 04_dependencies.yml) and update tasks/main.yml to delegate via include_tasks with run_once_web_app_bigbluebutton. Improve Greenlight admin creation behavior by treating the 'Email has already been taken' error as a non-fatal, unchanged outcome and running user:set_admin_role as a fallback, both for the primary password and the OIDC starred-password path.

Also standardize vhost flavour selection for services like Mailu, Discourse, CDN, Collabora, Coturn, OnlyOffice, Simpleicons and web-svc-logout by explicitly passing webserver_vhost_flavour where needed and aligning client_max_body_size and websocket configuration with the new webserver_* variables.

Reference: ChatGPT conversation https://chatgpt.com/share/6931c530-bba8-800f-9997-dd61dc1d497b

roles/web-svc-coturn/tasks/01_core.yml

@@ -5,5 +5,6 @@
     docker_compose_file_creation_enabled: true
     docker_git_repository_pull:           false
     docker_compose_flush_handlers:        true
+    webserver_vhost_flavour:              "basic"
 
 - include_tasks: utils/once/flag.yml