Implement filter checks: ensure all defined filters are used and remove dead code

Integration tests added/updated:
- tests/integration/test_filters_usage.py: AST-based detection of filter definitions (FilterModule.filters), robust Jinja detection ({{ ... }}, {% ... %}, {% filter ... %}), plus Python call tracking; fails if a filter is used only under tests/.
- tests/integration/test_filters_are_defined.py: inverse check — every filter used in .yml/.yaml/.j2/.jinja2/.tmpl must be defined locally. Scans only inside Jinja blocks and ignores pipes inside strings (e.g., lookup('pipe', "... | grep ... | awk ...")) to avoid false positives like trusted_hosts, woff/woff2, etc.

Bug fixes & robustness:
- Build regexes without %-string formatting to avoid ValueError from literal '%' in Jinja tags.
- Strip quoted strings in usage analysis so sed/grep/awk pipes are not miscounted as filters.
- Prevent self-matches in the defining file.

Cleanup / removal of dead code:
- Removed unused filter plugins and related unit tests:
  * filter_plugins/alias_domains_map.py
  * filter_plugins/get_application_id.py
  * filter_plugins/load_configuration.py
  * filter_plugins/safe.py
  * filter_plugins/safe_join.py
  * roles/svc-db-openldap/filter_plugins/build_ldap_nested_group_entries.py
  * roles/sys-ctl-bkp-docker-2-loc/filter_plugins/dict_to_cli_args.py
  * corresponding tests under tests/unit/*
- roles/svc-db-postgres/filter_plugins/split_postgres_connections.py: dropped no-longer-needed list_postgres_roles API; adjusted tests.

Misc:
- sys-stk-front-proxy/defaults/main.yml: clarified valid vhost_flavour values (comma-separated).

Ref: https://chatgpt.com/share/68b56bac-c4f8-800f-aeef-6708dbb44199

roles/sys-ctl-bkp-docker-2-loc/filter_plugins/dict_to_cli_args.py

@@ -1,36 +0,0 @@
-def dict_to_cli_args(data):
-    """
-    Convert a dictionary into CLI argument string.
-    Example:
-    {
-        "backup-dir": "/mnt/backups",
-        "shutdown": True,
-        "ignore-volumes": ["redis", "memcached"]
-    }
-    becomes:
-    --backup-dir=/mnt/backups --shutdown --ignore-volumes="redis memcached"
-    """
-    if not isinstance(data, dict):
-        raise TypeError("Expected a dictionary for CLI argument conversion")
-
-    args = []
-
-    for key, value in data.items():
-        cli_key = f"--{key}"
-
-        if isinstance(value, bool):
-            if value:
-                args.append(cli_key)
-        elif isinstance(value, list):
-            items = " ".join(map(str, value))
-            args.append(f'{cli_key}="{items}"')
-        elif value is not None:
-            args.append(f'{cli_key}={value}')
-
-    return " ".join(args)
-
-class FilterModule(object):
-    def filters(self):
-        return {
-            'dict_to_cli_args': dict_to_cli_args
-        }