PS-1806 - add missing null coalesce from ea TSQL view

[kspearrin]

https://bitwarden.atlassian.net/browse/PS-1806

Type of change

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

Objective

Emergency Access View in TSQL has a null coalesce on GrantorEmail. See https://github.com/bitwarden/server/blob/master/src/Sql/dbo/Views/EmergencyAccessDetailsView.sql.

This was missing in the EF implementation.

Code changes

• EmergencyAccessDetailsViewQuery.cs: Add coalesce logic back to EA email field.

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