Add IdentityServer license

[withinfocus]

Type of change

- [ ] Bug fix
- [ ] New feature development
- [ ] Tech debt (refactoring, code cleanup, dependency upgrades, etc)
- [ ] Build/deploy pipeline (DevOps)
- [X] Other

Objective

Adds the license issued to us from Duende for redistribution. Per:

https://docs.duendesoftware.com/identityserver/v6/fundamentals/license_key

we will load a default from our configuration and installations can override it if they desire.

Once this is in place the log warning "You do not have a valid license key for the Duende software." will no longer be emitted.

Code changes

• src/Core/Settings/GlobalSettings.cs: License key string property with a default.
• bitwarden_license/src/Sso/Utilities/ServiceCollectionExtensions.cs and src/Identity/Utilities/ServiceCollectionExtensions.cs: License usage.

Before you submit

• Please check for formatting errors (dotnet format --verify-no-changes) (required)
• If making database changes - make sure you also update Entity Framework queries and/or migrations
• Please add unit tests where it makes sense to do so (encouraged but not required)
• If this change requires a documentation update - notify the documentation team
• If this change has particular deployment requirements - notify the DevOps team