Numeric prefix to all network upgrades

[prasannavl]

Summary

• Adds a numeric prefix to all network upgrades: DF<num><name>
• This is important for code maintainability and readability. Provides better context on which fork comes after which more intuitively.
• Note: The first commit is pure automated refactor. Any other amendments to go after.
• Possible TODO: Add -df<num> flag aliases to make it easier.

Note: Might be better to wait for #1633 / #2068 iterations to be finished first before merging this.

Based on: #2291
Blocked by: #2068

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