Rename sqlparser_derive to sqlparser_procmacro, document features

[alamb]

Follow on from #765

rename crate to sqlparser_procmacro to be more consistent with other crates in the rust ecosystem

[alamb]

I plan to merge this once CI passes as I then plan to add CI tests for the other crate features

[alamb]

cc @tustvold

[tustvold]

_derive is more consistent with the ecosystem as whole for a derive macro?

[coveralls]

Pull Request Test Coverage Report for Build 3795008836

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 85.985%

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Totals
Change from base Build 3794845435:	0.0%
Covered Lines:	13007
Relevant Lines:	15127

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💛 - Coveralls

[alamb]

@tustvold notes prior art serde_derive, parquet_derive, etc -- will leave this alone