Configuration option to select specific fields for querying when "search all fields"

[Kxka]

What does this Pull Request do?

Provide a brief description of what the intended result of the PR will be and/or what
problem it solves.

• Related GitHub Issue: [FEATURE] Configuration option to select specific fields for querying when "search all fields" #76

What's new?

Added form with checkboxes to choose which fields to query from when using "searching all fields".
e.g. A collection with genre "test" will not show up when querying "test" if genre checkbox not chosen.

Default behaviour where no checkboxes are chosen, all fields are queried.

How should this be tested?

1. Create a dummy collection
2. Go to /admin/config/search/advanced and choose which fields to query from
3. Search the collection with the advanced search bar and "searching all fields" label (keyword)

Documentation Status

• Does this change existing behaviour that's currently documented?
• Does this change require new pages or sections of documentation?
• Who does this need to be documented for?
• Associated documentation pull request(s): ___ or documentation issue ___

Additional Notes:

Any additional information that you think would be helpful when reviewing this
PR.

Interested parties

Tag (@ mention) interested parties or, if unsure, @Islandora/committers

[Natkeeran]

This PR resolves an error that gets thrown when too many fields (https://stackoverflow.com/questions/16901299/too-many-boolean-clauses-exception-in-solr) are included for keyword search.

The approach is to add a config option to enable the user to select the fields that user wants to include for keyword search. The user can include Rendered HTML output as one of the fields.

Further, it fixes an issue related to search highlight by only showing highlighting if there are fields that can be highlighted.

Tested this with starter_dev. Works as described.