Add a crate to test the in-browser light client. (#4887)

Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>

substrate/Cargo.lock

@@ -3372,6 +3372,23 @@ dependencies = [
  "tempfile",
 ]
 
+[[package]]
+name = "node-browser-testing"
+version = "2.0.0"
+dependencies = [
+ "futures 0.3.4",
+ "futures-timer 3.0.2",
+ "jsonrpc-core",
+ "libp2p",
+ "node-cli",
+ "sc-rpc-api",
+ "serde",
+ "serde_json",
+ "wasm-bindgen",
+ "wasm-bindgen-futures",
+ "wasm-bindgen-test",
+]
+
 [[package]]
 name = "node-cli"
 version = "2.0.0-dev"
@@ -9075,6 +9092,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2cc57ce05287f8376e998cbddfb4c8cb43b84a7ec55cf4551d7c00eef317a47f"
 dependencies = [
  "cfg-if",
+ "serde",
+ "serde_json",
  "wasm-bindgen-macro",
 ]
 
@@ -9134,6 +9153,30 @@ version = "0.2.60"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "daf76fe7d25ac79748a37538b7daeed1c7a6867c92d3245c12c6222e4a20d639"
 
+[[package]]
+name = "wasm-bindgen-test"
+version = "0.3.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "648da3460c6d2aa04b715a936329e2e311180efe650b2127d6267f4193ccac14"
+dependencies = [
+ "console_error_panic_hook",
+ "js-sys",
+ "scoped-tls",
+ "wasm-bindgen",
+ "wasm-bindgen-futures",
+ "wasm-bindgen-test-macro",
+]
+
+[[package]]
+name = "wasm-bindgen-test-macro"
+version = "0.3.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf2f86cd78a2aa7b1fb4bb6ed854eccb7f9263089c79542dca1576a1518a8467"
+dependencies = [
+ "proc-macro2",
+ "quote 1.0.3",
+]
+
 [[package]]
 name = "wasm-gc-api"
 version = "0.1.11"