Instead of the current implementation, where we have lists of versions and LTS releases, we can have one list of versions that are each annotated with the requirements they satisfy. This can make future updates less error-prone, as it would be easier to reason about our various releases when we have to make changes to the file.

This might also make it easier to have our scripts infer the value of 'generateFCVLowerBoundOverride' (e.g. if it is set but null).

Example:

versions:
- fcv: "4.0"
  lts: true
- ...
- fcv: "4.4"
  lts: true
- fcv: "5.0"
  lts: true
  current: true
- ....
- "6.0"
  lts: true
- fcv: "100.0"