Add PagerOptions

[MikeAlhayek]

Add PagerOptions options.
Replace ISiteService use when possible by IOptions<PagerOptions>
Removed ISiteService when it's not used.

[jtkech]

@CrestApps

So I committed some last tweaks

• Re-use IShellConfiguration for PagerOptions and also ResourceOptions because both related projects still reference (maybe transitively) OC.Abstractions, so better to use IShellConfiguration.

• Renamed to PagerOptionsConfiguration and ResourceOptionsConfiguration to follow the naming we use most of the time (not always) for I[Post]ConfigureOptions<>.

• Commented out the OrchardCore_Navigation example in appsettings.json.

I'm waiting for your review ;)

[Skrypt]

Looks good to me by doing a quick vertical check.

[jtkech]

Okay cool then ;)