Feature/zen token

[renchenchang]

What does this PR do?
Shielded transaction by zk-snark. User can create shielded address and make shielded transactions which will not expose any information.

Why are these changes required?

This PR has been tested by:

• Unit Tests
• Manual Testing

Follow up

Extra details

[codecov-io]

Codecov Report

Merging #2352 into develop will decrease coverage by 3.73%.
The diff coverage is 16.88%.

@@              Coverage Diff              @@
##             develop    #2352      +/-   ##
=============================================
- Coverage       42.5%   38.77%   -3.74%     
- Complexity      4362     5007     +645     
=============================================
  Files            538      650     +112     
  Lines          32609    41443    +8834     
  Branches        3596     4249     +653     
=============================================
+ Hits           13861    16068    +2207     
- Misses         17406    23866    +6460     
- Partials        1342     1509     +167

Impacted Files	Coverage Δ	Complexity Δ
...in/java/org/tron/core/zen/note/NoteEncryption.java	73.91% <ø> (ø)	4 <0> (?)
...n/core/services/http/EasyTransferAssetServlet.java	3.5% <ø> (ø)	2 <0> (ø)	⬇️
...a/org/tron/core/services/http/ClearABIServlet.java	8.69% <ø> (ø)	2 <0> (ø)	⬇️
...a/org/tron/core/actuator/SetAccountIdActuator.java	65.95% <ø> (ø)	10 <0> (ø)	⬇️
.../tron/core/services/http/CreateAccountServlet.java	9.09% <ø> (ø)	2 <0> (ø)	⬇️
...core/services/http/GetBlockByLimitNextServlet.java	4.87% <ø> (ø)	2 <0> (ø)	⬇️
...a/org/tron/core/services/http/TransferServlet.java	9.09% <ø> (ø)	2 <0> (ø)	⬇️
...c/main/java/org/tron/core/net/TronNetDelegate.java	10% <ø> (ø)	4 <0> (ø)	⬇️
...rc/main/java/org/tron/core/services/http/Util.java	0% <ø> (ø)	0 <0> (ø)	⬇️
.../http/GetDelegatedResourceAccountIndexServlet.java	4.54% <ø> (ø)	2 <0> (ø)	⬇️
... and 380 more

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