Antlers runtime augment data collection values

[JohnathonKoster]

This PR fixes #7426 by augmenting instances of DataCollection if they are returned from tag callbacks, allowing the following to "just work":

{{ posts = { collection:blog } }}

{{ posts scope="post" }} {{ post:tags }} {{ title }} {{ /post:tags }} {{ /posts }}

[what-the-diff]

• The reduceForAntlers method was changed to use the new RuntimeValues::resolveWithRuntimeIsolation()
• A test for augmented assignment with tag results containing augmentable items was added
• A test for tags returning collections resolving correctly was added