Feat: Added event for new microblocks

[pavitthrap]

Description

Added events for unconfirmed microblocks for issue #2553. The event data includes the index_block_hash of the preceding block, filtered events (only includes the events from the receipts that each event observer is interested in), and transaction receipts.

Each payload may contain transactions from multiple microblocks. Each tx receipt comes with a tx_index, which starts from 0 for each microblock. Each tx receipt also includes the sequence number of the microblock it belongs to.

Notes

• One foreseeable "issue" is that different stacks nodes might have different microblock streams (in the case the leader is creating a microblock fork). If someone is querying the API through a load balancer endpoint, the load balancer could conceivably direct a user to different stacks nodes on each page refresh, which could lead to different data on the page. This might not be an important case to consider if most leaders are acting honestly, but something to consider.
• I could add more in-depth testing

Type of Change

• New feature
• Bug fix
• API reference/documentation update
• Other

Testing information

Ran microblock_integration_test in neon_integrations.rs. Ran cargo test.

[jcnelson]

LGTM! Just one minor comment to address.

[kantai]

LGTM! Just needs to do some merge conflict resolution.

[blockstack-devops]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.