Add source of command execution to CommandEventData

[Giorgi]

EF Core interceptors fire in response to every command/query no matter whether it was a Linq query or one of the raw query methods (FromSqlRaw, FromSqlInterpolated, ExecuteSqlRaw, etc) The event argument passed to the interceptor method doesn't indicate the type of the query or source of the command

Proposed solution:

Add an (enum) property to CommandEventData indicating the source of the query/command.

Thoughts?

[ajcvickers]

Duplicate of #23719. The solution you propose seems like a good place to start if you're thinking of doing a PR.