Key Delegation needs a protocol check

[dnpotter]

Key Delegation has the 'all-permissions' permission type, which gives the delegated key the same rights to all bubbles as the signing wallet key. This is clearly a security risk since an attacker could trick the user into unknowingly signing the hash of an all-permissions delegation giving the attacker full access to the user's bubbles.

Possible ways this could be prevented:

Firstly, remove the 'all-permissions' type. This is essential but means the Key Delegation becomes extremely restrictive without other changes, such as those below.

1. Add an 'application-protocol' code to each access control contract and have the Guardian check that the delegation includes that code, perhaps in a new 'application-permission' permission type. This could be implemented by:
   a) having getAccessPermissions return the code in every call, using most of the spare bits in the returned permissions field.
   b) add a new 'protocol' parameter to getAccessPermissions, which would allow the contract to restrict access itself.

2. Consider a replacement for Key Delegation, such as ProxyIds https://github.com/Bubble-Protocol/bubble-contracts#bubble-id

3. Encourage users to create a different wallet key for each application. Means the SDK does not need to be modified.

4. Any others?