change abstract from string to text

[seth-shaw-unlv]

GitHub Issue: Islandora/documentation#1977

See the conversation on Slack.

What does this Pull Request do?

Changes the abstract field from string to text to allow formatting, such as italics.

As a bonus, adds abstract to the other node display modes since it was only in default and not in binary, pdfjs, or openseadragon.

What's new?

• Changes the abstract field from string to text and updates the related form and view displays.
• Does this change require documentation to be updated? No
• Does this change add any new dependencies? No
• Does this change require any other modifications to be made to the repository
  (i.e. Regeneration activity, etc.)? This is for new installs.
• Could this change impact execution of existing code? No.

How should this be tested?

• Spin up an islandora_defaults, the abstract field won't allow formatting.
• Spin up a new islandora_defaults with the PR, the abstract field does support formatting.

Interested parties

@Islandora/8-x-committers, esp @rosiel.