Add self to raw transactions

[prd-fox]

When distributing a raw transaction to all the recipients, it may be that there are no recipients defined.
In this PR, we add ourselves as a participant so that there is always at least 1 recipient that we can use to decrypt a payload.

No acceptance tests have been added as they should be covered by the quorum-acceptance-test suite, and no tests currently exist in this project.

Fixes #895

[codecov-io]

Codecov Report

Merging #896 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##             master    #896      +/-   ##
===========================================
+ Coverage      99.4%   99.4%   +<.01%     
  Complexity     2093    2093              
===========================================
  Files           316     316              
  Lines          6081    6082       +1     
  Branches        312     312              
===========================================
+ Hits           6045    6046       +1     
  Misses            5       5              
  Partials         31      31

Impacted Files	Coverage Δ	Complexity Δ
...rum/tessera/thirdparty/RawTransactionResource.java	100% <100%> (ø)	4 <2> (ø)	⬇️
...um/tessera/transaction/TransactionManagerImpl.java	100% <100%> (ø)	37 <0> (ø)	⬇️

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