Fix Go bindings and enable in CI

- Fix all compilation errors in Go bindings
- Add missing type definitions (Pattern, ASTVector, ParamDescrs)
- Fix boolean comparisons to use bool() casts
- Fix Z3_app type casts using unsafe.Pointer
- Fix null symbol handling to use nil
- Fix unused variable in basic_example.go
- Fix CMake test target to run from examples/go directory
- Restore CI steps to build and test Go bindings

Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>

src/api/go/CMakeLists.txt

@@ -46,7 +46,8 @@ if(Z3_BUILD_GO_BINDINGS)
                 CGO_LDFLAGS=${CGO_LDFLAGS_VALUE}
                 LD_LIBRARY_PATH=${CMAKE_BINARY_DIR}:$ENV{LD_LIBRARY_PATH}
                 PATH=${CMAKE_BINARY_DIR}$<SEMICOLON>$ENV{PATH}
-                ${GO_EXECUTABLE} run ${CMAKE_SOURCE_DIR}/examples/go/basic_example.go
+                ${GO_EXECUTABLE} run basic_example.go
+            WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}/examples/go
             COMMENT "Running Go examples"
             DEPENDS libz3
             VERBATIM