Add fmt to miner, mempool and validation

[prasannavl]

Summary

• Add fmt to more key cpp elements
• Remove the .clang-format from Bitcoin that was never used anyway by BTC and replace it with ours.
• Start reformatting whitelists with miner, validation and mempool as they are often updated.

Blocked on:

• Add block and transaction context #2563
  • Includes many changes, better to add this to prevent conflicts

Implications

• Storage

  • Database reindex required
  • Database reindex optional
  • Database reindex not required
  • None

• Consensus

  • Network upgrade required
  • Includes backward compatible changes
  • Includes consensus workarounds
  • Includes consensus refactors
  • None