Add westend chain-spec and some chain-spec utilities

[clangenb]

This PR adds the following:

1. Hardcode the chain-specs for Bajun and Westend into the collator binary so that we don't need to copy chainspecs.json files to our servers.
2. Simplify adding new chain configurations by parametrizing chain-spec functions.
3. Add a script that generates wasm and chain and chain-spec for a chain-id

Todo:

• westend-local produces blocks (have to wait for 1 hour until the next session begins).
• Add westend parachain id