feat(core): require the user to choose a snapshot if the blocks flag is missing

[faustbrian]

Summary

Make the --blocks optional to make @adrian69 life easier with snapshots

1. If --blocks is available it will use that value
2. If the --blocks flag is missing and only 1 snapshot exists it will use that for restore and verify
3. If the --blocks flag is missing and multiple snapshots exist it will prompt the user to select one

What kind of change does this PR introduce?

• Bugfix
• New feature
• Refactoring / Performance Improvements
• Build-related changes
• Documentation
• Tests / Continuous Integration
• Other, please describe:

Does this PR introduce a breaking change?

• Yes
• No

Does this PR release a new version?

• Yes
  • All tests are passing
  • All benchmarks are passing without any major regressions
  • Sync from 0 works on mainnet
  • Sync from 0 works on devnet
  • Starting a new network and forging on it work
  • Explorer is fully functional
  • Wallets are fully functional
• No

Checklist

• I have read the CONTRIBUTING documentation
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)