fix: tokenClaimAirdrop throws NPE on null sender or receiver

[kimbor]

Description:
When submitting a tokenClaimAirdrop transaction, if one of the PendingAirdropIds in the list has an empty senderId or receiverId then the transaction fails catastrophically. This PR fixes the problem and adds unit tests and hapi tests to verify the fix.

Related issue(s):
Fixes #17095
Sister PR to develop: #17097

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ +0.00% (target: -1.00%)	✅ 100.00%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (abb296b)	98029	64272	65.56%
Head commit (658751e)	98033 (+4)	64276 (+4)	65.57% (+0.00%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#17096)	4	4	100.00%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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[lukelee-sl]

LGTM. Thanks for catching this.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.87%. Comparing base (abb296b) to head (658751e).
Report is 1 commits behind head on release/0.57.

Additional details and impacted files

@@               Coverage Diff               @@
##             release/0.57   #17096   +/-   ##
===============================================
  Coverage           63.86%   63.87%           
- Complexity          20576    20577    +1     
===============================================
  Files                2550     2550           
  Lines               95264    95268    +4     
  Branches             9952     9952           
===============================================
+ Hits                60845    60850    +5     
  Misses              30802    30802           
+ Partials             3617     3616    -1     

Files with missing lines	Coverage Δ
.../token/impl/handlers/TokenClaimAirdropHandler.java	76.85% <100.00%> (+0.79%)	⬆️

... and 1 file with indirect coverage changes