Add standalone utilities based on RPC methods

Description

This MR aims at implementing RPC methods based on the RPC methods and functions. Two utilities are created to prove the functionalities:

• gem-recover that recovers the back-end board
• gem-update-address-table that updates the LMDB address table after a firmware update

Using this opportunity to remove any dependency on the /mnt/persistent/gemdaq and /mnt/persistent/gemuser files.

Related Issue

How Has This Been Tested?

The code compiles and launching a run is possible through the updated instructions and new tools.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.