Refactor some registry lock verification code

[gbrodman]

The user, on the front end, should not be required to provide whether or not they're trying to verify a lock or an unlock. They should only need the verification code. We can inspect the lock object itself (and the domain in question) to see whether or not we're verifying a lock or an unlock.

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This change is 

[ptkach]

Reviewed 1 of 9 files at r1, 2 of 4 files at r2, all commit messages.
Reviewable status: 3 of 9 files reviewed, 1 unresolved discussion (waiting on @gbrodman)

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core/src/main/java/google/registry/tools/DomainLockUtils.java line 102 at r2 (raw file):

   * <p>This assumes that the lock object / domain in question has a pending lock or unlock.
   */
  public RegistryLock verifyLockAction(String verificationCode, boolean isAdmin) {

nit: verifyLockAndUnlockAction or maybe verifyVerificationCode, would be more suitable

[ptkach]

Reviewed 1 of 9 files at r1, 2 of 4 files at r2, 4 of 4 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @gbrodman)