enhancing solochain template (#5143)
Since we have a minimal template, I propose enhancing the solochain
template, which would be easier for startup projects.
- Sync separates `api`, `configs`, and `benchmarks` from the parachain
template
- introducing `frame-metadata-hash-extension`
- Some style update
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Co-authored-by: 
Kian Paimani <[email protected]>