Remove cargo metadata --frozen and --offline flags

cargo metadata resolves all dependencies even ones that are disabled (known as weak dependencies)
which cargo build doesn't do (see issue rust-lang/cargo#10801). These unresolved dependencies require
network access to load their package metadata.
As the `--frozen` flag itself blocks network access (in addition to blocking changes to the Cargo.lock)
too, we need to remove both the `--frozen` and `--offline` flags. Doing this allows cargo the change the
`Cargo.lock` though, which is undesirable (as we're in the process of building the same dependencies that
rely on the `Cargo.lock` in the first place).

build/config.rs

@@ -105,7 +105,6 @@ impl BuildConfig {
     pub fn with_cargo_metadata(&mut self) -> Result<()> {
         let metadata = cargo_metadata::MetadataCommand::new()
             .current_dir(workspace_dir()?)
-            .other_options(vec!["--frozen".into(), "--offline".into()])
             .exec()?;
 
         let root_package = match (metadata.root_package(), &self.esp_idf_sys_root_crate) {