Type safe mappings in query node

[joystream]

Type safe mappings in query node

[dzhelezov]

Related: #5

[dzhelezov]

Phase I

[ ] Load the manifest file into Hydra indexer context
[ ] Read the metadata file and extract type info about events and extrinsic defined in the manifest
- Add checks against the runtime metadata from the indexer
[ ] For each type, generate the import
- [ ] Figure out polkadot/api lib version
- [ ] Generate imports for standard types
- [ ] Figure out imports for custom types (generate from defs.json?)

Phase II

[ ] For custom types, register in the typeRegistry
[ ] Generate event typings based on the metadata
[ ] Generate extrinsic typings based on the metadata

Phase III

[ ] Add execution context to the processor
[ ] Rework the processing queue to support non-runtime events (block and extrinsic hooks)
[ ] Figure out additional steps (pre- and post- handlers) for the processor pipeline
[ ] Pass type-safe mappings parameters (extrinsic or event) together with the context to the mappers

[dzhelezov]

Introduced already in Hydra v2 (typegen)