put better `version` attr in stable/beta derivations

[cdmistman]

for replit/nixmodules i'd like to use fenix to supply the rust toolchains. i'd like to make the name of the nixmodules something like rust-1.73:... but that's not really feasible with fenix.

this pr changes the manifest generation and derivation construction for components.

• during manifest generation (update script), the version of the component is now included in the JSON object as a field, unedited
  • note: this has an unfortunate side-effect (see screenshot below)
• when building the component derivation, prefers the version from the component source instead of relying solely on the date of the component or the date the component was fetched

[cdmistman]

fyi @figsoda CI passes when i manually run locally, the reason why it's failing in CI is because the update script needs to be run since it adds a field to the data json files

i can do this first thing in the morning to ensure reproducibility with main