Fix for #1052 - ViewComponents should support fully qualified names

This change adds the concept of a full-name to viewcomponents. View
components can be invoked using either the short name or long name. If the
provided string contains a '.' character, then it will be compared against
full names, otherwise it will be matched against short names only.

The short name is used for view lookups.

If the name is explicitly set via ViewComponent attribute, then the full
name is the name provided. The short name is the portion of the name after
the last '.'. If there are no dots, then the short name and full name are
the same.

If the name is not set explicitly, then it is inferred from the Type and
namespace name. The short name is the Type name, minus the 'ViewComponent'
suffix (if present). The full name is the namespace of the defining class,
plus the short name.
Fix #1370 - Always use the provided formatter in JsonResult

The change here is to always use the provided formatter, instead of using
it as a fallback. This is much less surprising for users.

There are some other subtle changes here and cleanup of the tests, as well
as documentation additions.

The primary change is that we still want to run 'select' on a formatter
even if it's the only one. This allows us to choose a content type based
on the accept header.

In the case of a user-provided formatter, we'll try to honor the best
possible combination of Accept and specified ContentTypes (specified
ContentTypes win if there's a conflict). If nothing works, we'll still run
the user-provided formatter and let it decide what to do.

In the case of the default (formatters from options) we do conneg, and if
there's a conflict, fall back to a global (from services)
JsonOutputFormatter - we let it decide what to do.

This should leave us with a defined and tested behavior for all cases.
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