Remove stardust related code

[wulfraem]

Description of change

PR removes references to stardust client related code, except for the places where identity_stronghold is used, which itself in its implementation relies on it.

This includes parts of the IotaDocument unpacking and Resolver behavior.

IotaDocuments can now be unpacked via IotaDocument::unpack_from_iota_object_data, which is the replacement for the AliasOutput based IotaDocument::unpack_from_output.

IotaDocument::unpack_from_iota_object_data can also be used to parse OnChainIdentity::get_historys outputs, test and examples have been updated to test and showcase this.

IotaClientExt and IotaIdentityClientExt have been removed and their role in Resolver::attach_iota_handler and Resolver::attach_multiple_iota_handlers has been replaced by DidResolutionHandler with the sole function resolve_did to allow defining custom resolvers.

Type of change

Add an x to the boxes that are relevant to your changes.

• Bug fix (a non-breaking change which fixes an issue)
• Enhancement (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Fix

How the change has been tested

Ran tests locally to check, that existing functionality still works.

Change checklist

Add an x to the boxes that are relevant to your changes.

• I have followed the contribution guidelines for this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[UMR1352]

Only nitpicks. Good job