Avoid conflict with other SPM packages by renaming the CSQLite SPM target

[groue]

As reported by @jegnux, the SPM target "CSQLite" conflicts with other SPM packages such as SQLiteNIO. This prevents users from sharing server and client code in a single SPM package, and generally makes life more complicated than desired.

Maybe this will be solvable at the SPM level at some point (I'm not holding my breath), but currently it is just not possible. I don't see how this can be solved unless packages publish namespaced targets: CSQLite -> GRDBCSQLite or GRDB_CSQLite.

Since this is a breaking change for existing apps, this renaming will happen in GRDB 7.