Address duplication & missing test cases in registration commands

[sitetester]

What was the problem?

This PR resolves #8193

How was it solved?

• Current code throws error 'Validators blsKeys must be unique and lexicographically ordered', which doesn't explicitly tell whether it's unique or lexicographically ordered
• It addresses duplication in registration commands (& in their test files) by moving common code to parent class
• Missing tests added

How was it tested?

Tests are functional

[codecov]

Codecov Report

Merging #9043 (2219d68) into release/6.1.0 (5c689a9) will decrease coverage by 0.80%.
The diff coverage is 93.70%.

❗ Current head 2219d68 differs from pull request most recent head 8ab9a36. Consider uploading reports for the commit 8ab9a36 to get more accurate results

@@                Coverage Diff                @@
##           release/6.1.0    #9043      +/-   ##
=================================================
- Coverage          84.34%   83.54%   -0.80%     
=================================================
  Files                651      604      -47     
  Lines              23985    22697    -1288     
  Branches            3490     3346     -144     
=================================================
- Hits               20229    18962    -1267     
+ Misses              3756     3735      -21     

Files	Coverage Δ
...ommander/src/bootstrapping/commands/keys/create.ts	100.00% <100.00%> (ø)
elements/lisk-cryptography/src/encrypt.ts	97.22% <100.00%> (+0.02%)	⬆️
framework/src/application.ts	82.41% <100.00%> (ø)
framework/src/index.ts	100.00% <100.00%> (ø)
framework/src/modules/dynamic_reward/constants.ts	100.00% <ø> (ø)
framework/src/modules/dynamic_reward/endpoint.ts	100.00% <100.00%> (ø)
framework/src/modules/dynamic_reward/index.ts	100.00% <ø> (ø)
framework/src/modules/dynamic_reward/method.ts	71.42% <ø> (ø)
framework/src/modules/dynamic_reward/module.ts	96.55% <100.00%> (ø)
framework/src/modules/dynamic_reward/schemas.ts	100.00% <100.00%> (ø)
... and 13 more

... and 67 files with indirect coverage changes

[sitetester]

Need to rebase on release/6.1 branch

[ishantiw]

I think the PR is deviating from the issue. There is a lot of refactoring and its not required by the issue.