fix(balanced_mp): removes some panics, adds some checks and new tests

[sdbondi]

Description

• number of minor optimisations (e.g MergedBalancedBinaryMerkleIndexOrHash type vs tuple with index uint to Vec conversion)
• removed a number of possible panics
• adds integer underflow check in BalancedMerkleProof::verify
• adds edge case check for if all proofs to merge are zero height
• adds some extra tests for faulty proofs and "real world" data test
• minor memory optimisations
• format cargo.toml and reduce minimum required versions for some dependencies

Motivation and Context

None of these changes are game changing however they do address some important bugs that could prevent a bad actor from causing panics in a remote node.

@Cifko please check that I didn't break anything.

I wanted to investigate this because of an issue in a test in the DAN repo that fails with an invalid BMT even though all unmerged proofs are valid. I imported this data and strangely, the proof verifies (both in the previous code and code from this PR), so I was unable to track down the precise reason for the failure.

How Has This Been Tested?

New and existing unit tests

What process can a PR reviewer use to test or verify this change?

Run tests

Breaking Changes

• None
• Requires data directory on base node to be deleted
• Requires hard fork
• Other - Please specify

[github-actions]

Test Results (CI)

1 153 tests  +5   1 153 ✔️ +5   10m 5s ⏱️ - 5m 41s
     37 suites ±0          0 💤 ±0 
       1 files   ±0          0 ❌ ±0 

Results for commit 54ca4e2. ± Comparison against base commit 0c1e576.

♻️ This comment has been updated with latest results.

[github-actions]

Test Results (Integration tests)

  2 files  ±0  12 suites  ±0   17m 47s ⏱️ -7s
29 tests ±0  28 ✔️ ±0  0 💤 ±0  1 ❌ ±0 
31 runs  ±0  28 ✔️ ±0  0 💤 ±0  3 ❌ ±0 

For more details on these failures, see this check.

Results for commit 54ca4e2. ± Comparison against base commit 0c1e576.

[Cifko]

Perfect, thanks