Update db_state output to include metadata & remove corpus specificity

[joel-wright]

Description

Update db_state file to include metadata & family_id. Make db_state file smoothly support both CCLW & UNFCCC data whilst sending more information to the pipeline.

Type of change

Please select the option(s) below that are most relevant:

• Bug fix
• New feature
• Breaking change

How Has This Been Tested?

Existing tests extended/modified.

Reviewer Checklist

• The PR represents a single feature (small driveby fixes are also ok)
• The PR includes tests that are sufficient for the level of risk
• The code is sufficiently commented, particularly in hard-to-understand areas
• Any required documentation updates have been made
• Any TODOs added are captured in future tickets
• No FIXMEs remain

[diversemix]

Looks good to me