Context:

In code libraries implementing STAC spec, a good validation exercise is to read and write the official examples of the repository. A typical test case implemented in DotNetStac is to recreate the collection example from the referenced items. To have a comprehensive validation, values in title, extent, summaries... must be aligned.

Proposed Changes:

1. Align spatio-temporal values between items and collection in order to be able to reproduce examples from code for automatic tests validation
2. As discussed and proposed in stac_extensions and summaries #1077 and Clarified stac_extensions #1078, include the stac_extensions corresponding to the summarized fields

PR Checklist:

• This PR is made against the dev branch (all proposed changes except releases should be against dev, not master).
• This PR has no breaking changes.
• I have added my changes to the CHANGELOG or a CHANGELOG entry is not required.
• This PR affects the STAC API spec, and I have opened issue/PR #XXX to track the change.