Add commands: azmcp sql *

Add set of commands for Azure Sql* support, looking for guidance on what a good first set of commands would be (since Azure SQL has a large surface area).

Server List, Server Database List, Server Database Query seems like a good first set of commands:

```
azmcp sql server list
azmcp sql server database list
azmcp sql server database query
```

I wondered whether `database` should be a sub-command of server, or a sibling (like it is in az cli). I see that for Cosmos DB `container` is a sub-command of `database`, so the closest equivalent to this for sql would be to have database as a sub-command to server (not a sibling)

Beyond this initial scenario, it's been suggested we round out with the following commands, but we need to think about this given LLM effectiveness tails off when lots of Tools are loaded and MCP clients (like VSCode, Claude, don't have intelligent tool loading based on likely relevance)

Azure CLI Command Group | Suggested azmcp Equivalent | Description | Priority
-- | -- | -- | --
~az sql server list/show/create/delete~ | azmcp sql server list/show/create/delete | Manage logical SQL servers. | High
~az sql db list/show/create/delete/update~ | azmcp sql server database list/show/create/delete/update | Manage databases under a logical SQL server. | High
~az sql server firewall-rule~ | azmcp sql server firewall-rule list/add/delete | Manage IP-based firewall access. | Medium
az sql server ad-admin | azmcp sql server ad-admin show/create/delete | Manage Azure AD administrators. | Medium
az sql db export/import | azmcp sql server database export/import | BACPAC import/export. | Medium
az sql db restore | azmcp sql server database geo-restore/point-in-time-restore | Restore database to a specific time or from geo-replicated backup. | Medium
az sql db audit-policy | azmcp sql server database audit-policy show/update | Control database audit logs. | Low
az sql db tde | azmcp sql server database tde show/enable/disable | Transparent Data Encryption for databases. | Low
az sql db threat-policy | azmcp sql server database threat-policy show/update | Threat detection policy. | Low
az sql db list-usages | azmcp sql server database list-usages | Get resource usage stats for databases. | Medium
az sql db replication-link | azmcp sql server database replication-link list/delete | Manage geo-replication links. | Low
az sql db copy | azmcp sql server database copy | Duplicate a database within same/different server. | Low
az sql db logs | azmcp sql server database logs list | Query diagnostic logs. | Low