fix: Remaining clang-tidy unchecked optionals

[godexsoft]

High Level Overview of Change

This PR fixes remaining issues from bugprone-unchecked-optional-access.

API Impact

No impact.

[codecov]

Codecov Report

❌ Patch coverage is 87.23404% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.8%. Comparing base (ea02312) to head (cd33aae).

Files with missing lines	Patch %	Lines
include/xrpl/protocol/PublicKey.h	0.0%	3 Missing ⚠️
src/libxrpl/tx/paths/OfferStream.cpp	50.0%	1 Missing ⚠️
src/xrpld/consensus/LedgerTrie.h	0.0%	1 Missing ⚠️
src/xrpld/rpc/detail/PathRequest.cpp	50.0%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #6979   +/-   ##
=======================================
  Coverage     81.8%   81.8%           
=======================================
  Files         1010    1010           
  Lines        76162   76171    +9     
  Branches      7529    7526    -3     
=======================================
+ Hits         62307   62317   +10     
+ Misses       13855   13854    -1     

Files with missing lines	Coverage Δ
include/xrpl/tx/ApplyContext.h	100.0% <100.0%> (ø)
include/xrpl/tx/paths/OfferStream.h	100.0% <100.0%> (ø)
include/xrpl/tx/paths/detail/StrandFlow.h	93.2% <ø> (ø)
src/libxrpl/net/HTTPClient.cpp	70.9% <100.0%> (ø)
src/libxrpl/server/Manifest.cpp	85.7% <100.0%> (+0.2%)	⬆️
src/libxrpl/shamap/SHAMapInnerNode.cpp	96.5% <100.0%> (ø)
src/libxrpl/tx/ApplyContext.cpp	100.0% <100.0%> (ø)
src/libxrpl/tx/invariants/AMMInvariant.cpp	95.1% <ø> (ø)
src/libxrpl/tx/paths/BookStep.cpp	95.9% <100.0%> (+<0.1%)	⬆️
src/libxrpl/tx/paths/DirectStep.cpp	83.9% <ø> (ø)
... and 20 more

... and 5 files with indirect coverage changes

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[github-actions]

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