Define table links in files

[brotkrueml]

Configuration should not be stored in the database, instead files should be used. This has advantages:

• Configuration and its history can be versioned via Git.
• Configuration is deployable.

TYPO3 v12 will probably provide a way to read configuration from files and hydrate value objects accordingly, see discussion:
https://decisions.typo3.org/t/configuration-overhaul-plan/728

Prerequisite: #20

Acceptance criteria:

• Table links are defined in yaml files.
• An upgrade wizard to move the configuration from the database into yaml files is available.
• The backend module displays all available table links readonly. A connection check is possible.
• The Table and Column models and the TableRepository are removed.
• The sync hash, the last sync date and a possible error are stored in the registry.
• The field table_uid is removed from dataset and transfer table. Also the logic to use the table_uid as fallback when syncing datasets or transmitting transfers is in place.
• The documentation is adjusted.
• Add breaking entry to changelog

The following fields for a table link are available:

• identifier (string, unique, required, formerly know as "handle")
• type (string, required)
• connection identifier (string, required)
• table guid (string, required)
• custom table name (string optional/required, depends on type)
• columns (array, optional/required, depends on type)

The following fields for a column are available:

• name (string, required) - corresponds to column name from JobData table
• label (string, optional)
• type (string, required)
• decimal places (int, optional, depends on column type "decimal", default 2)
• field size (int, optional, depends on column type "text", defaults 0)
• alignment (string, optional, depends on table type "simple sync")
• sorting priority (int, optional, depends on table type "simple sync")
• sorting order (string (asc, desc), optional, depends on table type "simple sync", default asc)

Probably, one configuration file for each type is used.