Update EDTF field for 2018 spec compliance

[seth-shaw-unlv]

GitHub Issue: /Islandora-CLAW/CLAW/issues/995

What does this Pull Request do?

Fixes the Widget and Formatter for the EDTF Field Type to match the 2018 spec.

What's new?

• Adds an EDTFUtils class to consolidate EDTF-related code.
• Updates the validation code (now in EDTFUtils) to meet the 2018 spec.
• Updates the Widget and Formatter to use EDTFUtils and meet the spec.
• Adds an update hook to bring existing content in EDTF fields to meet the 2018 spec.

How should this be tested?

• Take a site with controlled_access_terms enabled and add some content to EDTF fields (repository items, taxonomy terms, whatever). They all comply with the 2012 spec.
• Apply the PR
• Run updates (either 'siteurl/update.php' or drush updb -y)
• Clear cache.
• Check your content. All the values should display correctly (even if exact wording and display has been adjusted) and viewing them in the edit window should show new signifiers. E.g. '?~' is now '%' and unspecified values 'u' are now 'X'.

Interested parties

@Islandora-CLAW/committers

[rosiel]

Works - I tested that it successfully transformed my 2012-style ETDF to 2018-ese.

[seth-shaw-unlv]

Ah! Hold up. Yes, it works for the dates; however, I didn't update EDTFConverter to expect 2018 compliant dates; it still assumes older ones.

[seth-shaw-unlv]

Would you mind reviewing again, @rosiel, so we can get this merged? Thanks.

[rosiel]

Tested again, ran it through some paces. Looks good!

[dannylamb]

Please feel free to merge when ready @rosiel. No 24h wait period here 🎉