Add dummy relying party (#19)

# Motivation

Add a new project to the SDK: Dummy Relying party.

This project should help issuer install a relying party to test the e2e
flow.

In this PR, I add the canister with the relying party.

In later PRs, we can style it better and expose the wasm from the Github
actions on releases so that developers can install it the same way they
install Internet Identity.

# Changes

* Create a Cargo project in the root.
* Create a new canister within `dummy-relying-party` which is based on
the [custom assets
example](https://github.com/dfinity/response-verification/tree/main/examples/http-certification/custom-assets).
* Add frontend assets to perform credential requests based on user
input. (See video for more details)

# Tests

I tested it with the Attendance project both in local replica and in
mainnet.

# Todos

- [ ] Add entry to changelog (if necessary).

.gitignore

@@ -5,3 +5,17 @@ dist
 # Editor settings
 .vscode
 .idea
+
+# dfx temporary files
+.dfx/
+canister_ids.json
+.env
+
+# built canisters
+*.wasm
+*.wasm.gz
+
+# Generated by Cargo
+# will have compiled files and executables
+debug/
+target/

CHANGELOG

@@ -2,6 +2,10 @@
 
 Changes in the upcoming versions.
 
+## New projects
+
+- Dummy relying party.
+
 ## Breaking Changes
 
 - Change the type of `CredentialData.credentialSubject` to `Principal`.