fix: did type in message crates

Resolves https://github.com/hyperledger/aries-vcx/issues/1165

Use did_parser_nom's Did type in message crates instead of string so as to parse & verify DIDs upon message deserialization

Hi @GHkrishna please have a look at my comment in your previous PR: https://github.com/hyperledger/aries-vcx/pull/1171#issuecomment-2035928469

Given things as they are, the code doesn't compile, the changes you made need more sync up across the codebase.

@GHkrishna In your local project directory, try running cargo clippy in the terminal. This will show up some of the things that you will need to do for your fix to be correct and complete.

Once you have taken care of the clippy suggestions, your code should compile.
We can then assist you further.

Best regards.