Sma 523 add open access until date

[mwbenowitz]

Description

This adds opds:since and opds:until parameters to the availability object for open source materials

Motivation and Context

This allows client applications to create "loan-like" behavior for open source materials without generating loan objects internally. These can have loan length configured at the collection/library level and help support several projects involving the Circulation Manager

How Has This Been Tested?

I have run this code locally with open source material and added an applicable unit test

Checklist:

• [x] I have updated the documentation accordingly.
• [x] All new and existing tests passed.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (662cc7e) 92.56% compared to head (b579692) 92.56%. Report is 3 commits behind head on develop.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #1910 +/- ## ======================================== Coverage 92.56% 92.56% ======================================== Files 216 216 Lines 43660 43665 +5 ======================================== + Hits 40413 40418 +5 Misses 3247 3247 ```

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