feat: custom derivation paths in Mnemonic ECDSA private key derivation

[bguiz]

Description:

What

• Add custom derivation path capability

Why

• Compatibility/ parity with EVM dev tools + wallets. Specifically:
  • When working Metamask, you need to use the hardcoded derivation path in it, and in SDK there's also a (different) hardcoded derivation path.
  • In EVM dev tools - web3.js/ethers.js/viem etc - they allow you to specify a custom derivation path, and do not force you to use the Ethereum one.
• The lack of support for custom derivation paths is a friction point for EVM developers onboarding into Hedera development
  • This may have the effect of effectively discouraging use of the SDK, in favour of using 3rd party libraries that do support custom derivation paths
• we should aim to reduce the reliance on 3rd party dependencies in general, within code that is written using the SDK
  • The following examples demonstrate that (1) additional code is needed, and (2) additional 3rd party dependencies need to be brought in:
  • example of extra code required in JS: https://github.com/hedera-dev/scratch-hello-world/blob/60fa4007/js-hello-world/00-create-fund-account/script-create-fund-account.js#L19-L23
  • example of extra code required in Java: https://github.com/hedera-dev/scratch-hello-world/blob/60fa4007/java-hello-world/00-create-fund-account/src/main/java/createfundaccount/ScriptCreateFundAccount.java#L30-L55
  • example of extra code required in Go: https://github.com/hedera-dev/scratch-hello-world/blob/60fa4007/golang-hello-world/00-create-fund-account/script-create-fund-account.go#L37-L61

Related issue(s):

Fixes: https://github.com/hashgraph/hedera-sdk-java/issues/1263#issuecomment-1330953933

Notes for reviewer:

• Related: https://github.com/hedera-dev/scratch-hello-world/pull/1
• Discussion with @thenswan + @0xivanov: https://swirldslabs.slack.com/archives/C0453UVBR42/p1717898573711519?thread_ts=1717061977.081859&cid=C0453UVBR42
• Related: https://github.com/hashgraph/hedera-sdk-java/pull/1842
• Related: https://github.com/hashgraph/hedera-sdk-go/pull/958

Checklist

• [x] Documented (Code comments, README, etc.)
• [x] Tested (unit, integration, etc.)

[sonarcloud[bot]]

Quality Gate failed

Failed conditions
11.8% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 54.66667% with 34 lines in your changes missing coverage. Please review.

Project coverage is 75.99%. Comparing base (5c428d4) to head (46cab9b). Report is 82 commits behind head on main.

:exclamation: Current head 46cab9b differs from pull request most recent head 5a5b32d

Please upload reports for the commit 5a5b32d to get more accurate results.

Files	Patch %	Lines
src/Mnemonic.js	54.66%	34 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2341 +/- ## ========================================== - Coverage 76.49% 75.99% -0.51% ========================================== Files 304 230 -74 Lines 75800 58047 -17753 ========================================== - Hits 57986 44114 -13872 + Misses 17814 13933 -3881 ```

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[bguiz]

@svetoslav-nikol0v + @thenswan 5a5b32d2

Attempt to increase code coverage of src/Mnemonic.js --> https://app.codecov.io/gh/hashgraph/hedera-sdk-js/pull/2341?src=pr&el=tree#23d3b499f82e11bd737b0faf0152911f-R153

Further context: https://swirldslabs.slack.com/archives/C0453UVBR42/p1719635439040999?thread_ts=1717061977.081859&cid=C0453UVBR42