Server tags and routing hints

Allow admins to tag servers with a short string (e.g. a location or special configuration like eu or large), and then allow front-ends to request new meetings on a specific type of server via metadata.

Let's mimic the Scalelite API for now:

• The meta parameter meta_server-tag can contain a semicolon-separated list of tags, and an optional ! at the end.
• If the meta parameter is missing or empty, the meeting is created on untagged servers only.
• If the value ends with !, only servers matching one of the requested tags are considered for new meetings.
• If the value does not end with !, matching servers are preferred, but untagged servers are also considered if no matching server is available.

Examples:

• meta_bbblb-select= (or missing): Start new meetings on untagged servers only.
• meta_bbblb-select=large;verylarge!: Start new meetings on servers tagged with large or verylarge only.
• meta_bbblb-select=large;verylarge: Start new meetings on servers tagged with large or verylarge, and fall back on untagged servers if no matching servers are available.

This can be used in combination with tenant based call parameter overrides to route specific tenants to specific servers only.

Trace the API handling of the meta_bbblb-select parameter and the server-selection entry point used when creating meetings. Verify how tenant-based call parameter overrides reach that selection logic. Done means admins can assign tags, matching tags are preferred or enforced according to the trailing !, and missing or empty metadata selects untagged servers only.