Call walproposer from Rust (#5403)

Create Rust bindings for C functions from walproposer. This allows to
write better tests with real walproposer code without spawning multiple
processes and starting up the whole environment.

`make walproposer-lib` stage was added to build static libraries
`libwalproposer.a`, `libpgport.a`, `libpgcommon.a`. These libraries can
be statically linked to any executable to call walproposer functions.

`libs/walproposer/src/walproposer.rs` contains
`test_simple_sync_safekeepers` to test that walproposer can be called
from Rust to emulate sync_safekeepers logic. It can also be used as a
usage example.

Cargo.lock

@@ -6092,6 +6092,17 @@ dependencies = [
  "winapi-util",
 ]
 
+[[package]]
+name = "walproposer"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "bindgen",
+ "postgres_ffi",
+ "utils",
+ "workspace_hack",
+]
+
 [[package]]
 name = "want"
 version = "0.3.0"