RepositoryBase - Add support for deferring save changes calls

[Psypher9]

When working with Entity Framework or EntityFramework Core, there needs to be a way to skip the implicit call to SaveChanges or SaveChangesAsync

Proposed options:

Option 1 - New IImmediateRepository and IReadOnlyImmediateRepository interfaces to support the immediate save changes

Example:

// currently
await _thingsRepo.AddAsync(newThing);

// instead
await _thingsRepo.AddImmediateAsync(newThing);

Where the existing methods will not immediately call for SaveChanges until UpdateAsync is called

Option 2 - optional parameter to apply immediately

// currently applying immediately
await _thingsRepo.AddAsync(newThing);

await _thingsRepo.AddAsync(newThing, applyImmediately: true);

[Psypher9]

Option 2 seems to be looking better to me right about now