New feature fast-runtime-10m was added.

This adds new rococo-runtime blob with hard-coded epochDuration. This
prevents from manipulating the state to change the runtime constants.

This commit also allows to remove `RococoGenesisExt` hack.

In this commit:
- all references to `RuntimeGenesisConfig` are removed,
- `RococoGenesisExt` is removed. It was the hack to allow overwriting `EpochDurationInBlocks` (1m/10m/60m rococo runtimes are now available),
- all `(kusama|polkadot|versi|rococo|wococo)_(staging|dev)_genesis_config` functions now return the JSON patch for default runtime `GenesisConfig`,
- ChainSpecBuilder is used, `from_gensis` is removed,

…ort-for-genesis-builder-api

Explicitly building fast-runtime version of rococo runtime is no longer
done.

Environment variables which control the time::EpochDurationInBlocks value were added:
- ROCOCO_FAST_RUNTIME - enables the fast runtime version of runtime with
  default value of EpochDurationInBlocks set to 10. Value of env does
  not matter.
- ROCOCO_EPOCH_DURATION - enables the fast runtime version with provided
  value of EpochDurationInBlocks (epoch duration will be set to the
  value of env).

Examples:
- to build runtime for `versi_staging_testnet_config which had
  EpochDurationInBlocks set to 100:
```
ROCOCO_EPOCH_DURATION=100 cargo build -p rococo
```
- to build runtime for `versi_staging_testnet_config which had
  EpochDurationInBlocks set to 100:
```
ROCOCO_EPOCH_DURATION=100 cargo build -p rococo-runtime
```
- to build runtime for `wococo_development`
```
ROCOCO_EPOCH_DURATION=10 cargo build -p rococo-runtime
or
ROCOCO_FAST_RUNTIME=1 cargo build -p rococo-runtime
```

…ort-for-genesis-builder-api

…ort-for-genesis-builder-api

…ort-for-genesis-builder-api

…ort-for-genesis-builder-api

…inSpec