state.sqlserver: Add support for Azure AD auth (+ metadata.yaml)

[ItalyPaleAle]

Adds support for Azure AD authentication in the state.sqlserver component.

Fixes #2726

1. First, the library we used is now deprecated and replaced by an official, Microsoft-maintained fork: https://github.com/microsoft/go-mssqldb - updated to use that library
2. Second, although the library did already support Azure AD auth (by importing a separate package), it did in a way that was not compatible with the shared Azure auth library all other components use.
   • It's now possible to authenticate with Azure AD by setting useAzureAD: true in the metadata.
   • The other Azure AD-related options are required as usual (like "azureClientID", etc)
   • A connectionString is still required to include the URL of the database, the DB name, and any connection option. If it contains credentials, they are ignored
3. This required doing some refactoring on the metadata parsing and struct
4. Also added the metadata.yaml

Note: I confirmed tests pass locally, but I can't easily add them to the certification tests because it appears I may need to create a separate Azure SQL instance to use Azure AD. I can look into doing that in a subsequent PR

[DeepanshuA]

Some nitpicks

[giovanidecusati]

Hi Team,

Just want to say thank you for the work you are doing and have considered implementing support for AAD for the SQL server state store. Looking forward to version 1.11! We are using Dapr on Azure Container App. I hope the Azure team doesn't take long to update to the new version.
Cheers,