Adding option to automatically define block names in RGMB mesh generators from region ID

[shikhar413]

Motivation

The Griffin team needs a way to define block names from RGMB mesh generators for each region ID, as lumping all blocks in the mesh into just two blocks - one for tri elems and one for quad elems - is not sufficient. The ability to define custom block names through RGMB mesh generators currently exists, but this is a manual process and can be cumbersome for larger meshes. The option to automatically do this based on the region ID of the element would streamline this process.

Design

Add a parameter region_id_as_block_name in ReactorMeshParams, which will act as a global variable within the RGMB system to inform RGMB MG's that the block name should be defined as <RGMB_PREFIX>_REG_<REGION_ID>. If the element is a tri element, the suffix "_TRI" will be added.

Impact

More flexible workflows that can be used by Griffin directly. Currently, the workaround to enable such functionality is to instead define an additional MG in Griffin to convert extra element id's to block id's