Fix duplicates v1 txt records

[chdwlch]

• Removed DO code
• Added a step to check for an existing record via CloudFlare API before attempting to create the record
• Returns a 409 in the creation attempt instead of 400 if a duplicate is found at that point
  Resolves: Investigate duplicate DNS records #6, Deprecate DigitalOcean #13

# create bip353
curl -X POST http://localhost:3000/record -H "Content-Type: application/json" -d  '{"localPart": "cw-test-72", "bolt12": "lno....1234567890"}'
{"message":"Bolt12 Address Created"

# duplicate with same values
curl -X POST http://localhost:3000/record -H "Content-Type: application/json" -d  '{"localPart": "cw-test-72", "bolt12": "lno....1234567890"}'
{"message":"Name is already taken."}

# duplicate with different values
curl -X POST http://localhost:3000/record -H "Content-Type: application/json" -d  '{"localPart": "cw-test-72", "bolt12": "lno....12345678901"}'
{"message":"Name is already taken."}

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[sbddesign]

Tested, works for me