[Jungfrau] Add Gain setting to Jungfrau notebooks

Description

This MR brings gain settings to Jungfrau constants, allowing to differentiate between different operating conditions.

The gain settings are saved in RUN section of files as settings and are:

dynamicgain: G0, G1, G2
dynamichg0: HG0, G1, G2
fixgain1: G1 
fixgain2: G2 
forceswitchg1
forceswitchg2

The expected configurations are then, for dark notebooks:

Runs taken with dynamicgain, forceswitchg1, forceswitchg2 -> gain_setting = 0
Runs taken with dynamichg0, forceswitchg1, forceswitchg2 -> gain_setting = 1

and for correction:

settings == dynamicgain -> gain_setting = 0
settings == dynamichg0 -> gain_setting = 1

How Has This Been Tested?

I tested the creation of local constants, but I did not test injection and retrieval to/from the database.

Relevant Documents (optional)

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

Reviewers

@calibration

@mramilli FYI.