feat(rust): Implement dht_provide() and dht_get_providers()

[rafal-ch]

Description

• Add dht_provide() and dht_get_providers().
• fn identity() functions returns identity, not just peer id

Related Issue(s)

This is one of the pieces needed for input-output-hk/hermes#630

Please confirm the following checks

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• 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
• Any dependent changes have been merged and published in downstream module

[github-actions]

📚 Docs Preview

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https://docs.dev.projectcatalyst.io/libs/630_pre_publish_step

[github-actions]

✅ Test Report | ${\color{lightgreen}Pass: 583/583}$ | ${\color{red}Fail: 0/583}$ |