Postgres: extension loading

[SuperSandro2000]

• we need an intermediate option in the form of listOf str to load inbuild modules per SQL (see https://c3d2.social/@sophie@catgirl.cloud/114109970398053904)
• the extension and shared object names should be taken from passthru and fallback to pname. (also see https://c3d2.social/@sophie@catgirl.cloud/114109970398053904)