Add Admin app

[prd-fox]

Adds an "Admin app" that contains API endpoints for node management resources, which may require different access settings (read: TLS) than the 3rd Party app.

Fixes #543

[codecov-io]

Codecov Report

Merging #596 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##             master     #596      +/-   ##
============================================
+ Coverage     99.48%   99.48%   +<.01%     
- Complexity     1724     1725       +1     
============================================
  Files           265      266       +1     
  Lines          5284     5289       +5     
  Branches        259      259              
============================================
+ Hits           5257     5262       +5     
  Misses            5        5              
  Partials         22       22

Impacted Files	Coverage Δ	Complexity Δ
.../java/com/quorum/tessera/admin/ConfigResource.java	100% <ø> (ø)	7 <0> (?)
...c/main/java/com/quorum/tessera/config/AppType.java	100% <100%> (ø)	5 <0> (ø)	⬇️
...in/java/com/quorum/tessera/admin/AdminRestApp.java	100% <100%> (ø)	1 <1> (?)
...com/quorum/tessera/config/cli/AdminCliAdapter.java	98.36% <100%> (ø)	8 <2> (ø)	⬇️

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