rust: Rename flag providers for clarity

Rename the Rust flag and export info providers to make it more clear
when workign with the Rust exporter vs the cc exporter.

Also renames a test for additional clarity.

Test: m blueprint_tests
Change-Id: I652b55ef000a2cd00f47b1dbfe86713c33ae9d63
diff --git a/rust/rust_test.go b/rust/rust_test.go
index 858c4db..4390f55 100644
--- a/rust/rust_test.go
+++ b/rust/rust_test.go
@@ -432,7 +432,7 @@
 	}
 }
 
-func TestRustRlibs(t *testing.T) {
+func TestRustFFIRlibs(t *testing.T) {
 	ctx := testRust(t, `
 		rust_ffi_static {
 			name: "libbar",