Breaking: Remove project specific custom fields 

Description 

EXT:academic_bite_jobs provides flexform options and filters based on custom project specific fields and options not interchangeable with other projects and not making sense being provided by default.

These custom fields needs to be setup the same way on the external bite-job system and is mosts likely not the way to go.

Mangling around with the current implementation even if only the options are removed is not suitable and the internal implementation needs to be streamlined first before adding customization endpoints in a reasonable way as public API.

Based on aforementioned background project specific implementation and options are now removed to clean up the code base as preparation to streamline first the internal implementation with dedicated changes, re-introducing the feature with a new API at a later point.

This is technically breaking, at least for the one specific project and is handled as breaking for it, albeit it should not target any other project at all.

Reducing the feature set to the bare minimum simply displaying only the single job detail page without related jobs is the mostly used base ground and the essential base feature to start fresh from.

Additionally, fluid template structure is streamlined in the same step to follow the restructure epic for all academic extensions.

Impact 

Following removals are included:

• flexform options settings.jobs.custom.zuordnung and

settings.jobs.groupBy are removed. `BiteFieldsHelper` is removed being unused and an empty class anyway. BiteJobsService->fetchBiteJobs() handling code for removed flexform setting options is removed from method. `public BiteJobsService->findCustomJobRelations()` is removed. public BiteJobsService->findCustomBiteFieldLabelsFromOptions() is removed. `public BiteJobsService->groupByRelations()` is removed. public BiteJobsService->mapFieldsToJobs() is removed.

Affected Installations 

EXT:academic_bite_jobs before v2.1 installations using custom project specific fields and options

Migration 

The settings stay in the stored FlexForm of a content element. From version 3.0 on the upgrade wizard academicBiteJobs_listViewFlexFormUpgradeWizard removes them; until then settings.jobs.groupBy still reaches the plugin and groups the list by a field the job postings no longer carry.

The same version renamed the view values ListView, CardView and TableView of the plugin settings to List, Card and Table without migrating them, so a content element saved with 2.0 failed to render. From version 3.0 on the old values render again, and the upgrade wizard academicBiteJobs_listViewFlexFormUpgradeWizard rewrites them, see Important: The job list groups only on request and reads old view values.

The grouping of the job list is configured in TypoScript since version 3.0, with plugin.tx_academicbitejobs.settings.jobs.groupBy, see Grouping the jobs.

The filter by a custom field and the grouping by its value are possible again since version 3.0, with two event listeners of the project and the TypoScript setting above, see Feature: Request and result events for the B-ITE job list and Example: a custom field filter and a grouping.