feature: Blockchain scanner PoC

[mpguerra]

Motivation

We want to investigate an approach to blockchain scanning in zebra using existing crates.

Specifications

One potential approach would be to send a single compactblock from a test function to the existing crate and check the results.

We can then try with multiple blocks or other more complex scenarios.

Possible Design

• Read blocks from disk and convert them into CompactBlocks - poc(scanner): get started with the blockchain scanner proof of concept #7758
• Parse a hard-coded viewing key - test(scan): Scan the first 10 blocks with the ZECpages viewing key #7903

Follow Up Task

• Admin: Add a branch protection rule for Build crates individually / Build zebra-scan crate

[teor2345]

Creating a new git repository with a binary crate, or adding an example binary to a new or existing Zebra crate might be simpler than a test function.

It depends if we want to iterate on the proof of concept to build the final product, or just do something quick to show it works, and throw it away.