RUST-DB: Expose creation and deletion symbols as C symbols

CMakeLists.txt

src/main/server.c

src/rust/liblektor-rs/inc/liblektor-rs/database.h

src/rust/liblektor-rs/src/database/mod.rs

src/rust/liblektor-rs/src/database/models.rs

src/rust/liblektor-rs/src/database/unsafe_interface.rs