Refactor DID identifier and add placeholder for network name instead of having "hedera" hardcoded

[hendrikebbers]

We should refactor the DID identifier (as example in

hiero-did-sdk-python/tests/unit/did/common.py

Line 17 in 523aae3

IDENTIFIER = f"did:hedera:{NETWORK}:{PUBLIC_KEY_DER}_{DID_TOPIC_ID_1}"

) and add a placeholder instead of having hedera hard coded. This will allow us to use the lib with other Hiero-based networks next to Hedera.

It will be fine to have an easy way to create it for hedera (like did.forHedera() or something) but it should be configurable.

[AlexanderShenshin]

Hi @hendrikebbers! This is a good point for vendor-neutral approach in Hiero, but I think we need to address this on Hedera DID spec level first.

did:hedera is a DID Method prefix defined in the spec. Also see DID syntax reference in W3C spec.

We may want to rename Hedera DID Method to Hiero DID Method.

[AlexanderShenshin]

@Reccetech ^