sqlite3-test: New package for running sqlite3 automatic tests.

This is a separate package because the sqlite3 autoconf distribution
doesn't have any automatic tests itself.

XXX This doesn't actually test the sqlite3 that was built and installed
for pkgsrc -- it builds several of its own sqlite3 binaries, under
different build configurations, and tests those instead.  To be fixed.

PR pkg/59243: databases/sqlite3: missing test target