Adds SQLCipher Custom Fork documentation

[R4N]

Adds SQLCipherCustomFork.md documentation. Adjusts README.md Encryption section to reference officially supported GRDB + SQLCipher fork and link SQLCipherCustomFork.md documentation.

This is a documentation update which includes instructions for creating a custom fork of GRDB w/SQLCipher to support requirements outside of the scope of the official fork.

Official Fork link has a placeholder of <url to official fork coming soon>

Pull Request Checklist

• CONTRIBUTING: You have read https://github.com/groue/GRDB.swift/blob/master/CONTRIBUTING.md
• BRANCH: This pull request is submitted against the development branch.
• DOCUMENTATION: Inline documentation has been updated.
• DOCUMENTATION: README.md or another dedicated guide has been updated.
• TESTS: Changes are tested.
• TESTS: The make smokeTest terminal command runs without failure.

[groue]

Hello @R4N! Glad to see you again :-)

This is a very valuable contribution! It can't be merged because of the reference to <url to official fork coming soon>, though. This fork is not needed for this documentation to be relevant. Things should be done one after the other.

Do you think it is possible to reword this document and the README changes, and remove this reference?

Also, based on the existing "Custom SQLite Builds" document, I suppose "Custom SQLCipher Builds" would be a better wording than "Custom SQLCipher Fork" (same for the name of the file).

Thank you very much!

[R4N]

@groue Great, Looks like the 7.10.0 release was well received! 🥳

I've replaced the reference to <url to official fork coming soon> in README.md and CustomSQLCipherBuilds back to the instructions for forking GRDB using the instructions in the Package.swift for now. As you mentioned we can always adjust that back when we establish an official fork.

Good suggestion about the rename of the file/title of the document. That's also been adjusted now.

[groue]

Hi @R4N,

Yes, v7.10.0 is welcome, we did a good work :-)

I let you decide if you want to address #1854 before or after this pull request. If you want to address #1854 first, you might want to restore the URL of the official fork here. I let you decide your preferred option, and I'll follow your path.

[R4N]

@groue

Excellent. Thanks!

I did end up opening up the new fork first: https://github.com/sqlcipher/GRDB.swift so I've adjusted the documentation to link over to that in this pull request.

[sebastiangarbarek]

Thank you both for doing this, I have a project using GRDB that's pulling in SQLCipher from a new SDK so this fork has been a blessing. Are there any plans to do the same for https://github.com/groue/GRDBSnapshotTesting?