Remove the no_std feature from the WASM builder (#3640)

* Remove the no_std feature from the WASM builder

* Address review

* More fixing

* Address review again

* Fix missing Cargo.lock

substrate/core/utils/wasm-builder/src/lib.rs

@@ -25,7 +25,6 @@
 //!
 //! 1. Add a `build.rs` file.
 //! 2. Add `substrate-wasm-builder-runner` as dependency into `build-dependencies`.
-//! 3. Add a feature called `no-std`.
 //!
 //! The `build.rs` file needs to contain the following code:
 //!
@@ -42,8 +41,6 @@
 //! }
 //! ```
 //!
-//! The `no-std` feature will be enabled by WASM builder while compiling your project to WASM.
-//!
 //! As the final step, you need to add the following to your project:
 //!
 //! ```ignore