Add Additional Bag-info.txt Configuration

Overview of the Feature Request
UVA is ingesting bags to APTrust and would like to have the tag (line) "Bag-Group-Identifier" in bag-info.txt. This tag is part of APTrust's spec: https://aptrust.github.io/userguide/bagging/

What kind of user is the feature intended for?
Sysadmin

What inspired the request?
Ingesting bags into APTrust which ingests many different collections. APTrust uses the tag "Bag-Group-Identifier" to find all items for a given "group" in APTrust's interface.

What existing behavior do you want changed?
To add a new JVM option to customize this new bagit-info.txt configuration:
https://guides.dataverse.org/en/latest/installation/config.html#configuring-bag-info-txt

Suggesting to have a new customization configuration to add

Bag-Group-Identifier

to the bag-info.txt file with a JVM configuration option, like this:

dataverse.bagit.sourceorg.groupidentifier

and have out of the box configuration write bag-info.txt files with:

Bag-Group-Identifier: <Group identifier>

Start with the bag-info.txt configuration described in the installation config guide and trace the JVM-option entry point that writes bag metadata. Done means the new Bag-Group-Identifier setting can be customized and generated bag-info.txt files contain the requested tag and value.