feat(rpc): add toncenter jrpc api

[Rexagon]

Alternative subset of methods for #588

[codecov]

Codecov Report

Attention: Patch coverage is 10.09709% with 926 lines in your changes missing coverage. Please review.

Project coverage is 44.57%. Comparing base (313a8ed) to head (1722b4e).
Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
rpc/src/endpoint/toncenter/models.rs	9.54%	453 Missing and 2 partials ⚠️
rpc/src/endpoint/toncenter/mod.rs	0.00%	269 Missing ⚠️
rpc/src/state/mod.rs	31.29%	99 Missing and 2 partials ⚠️
rpc/src/util/jrpc_extractor.rs	0.00%	41 Missing ⚠️
rpc/src/endpoint/mod.rs	0.00%	16 Missing ⚠️
rpc/src/endpoint/jrpc/mod.rs	0.00%	14 Missing ⚠️
rpc/src/endpoint/proto/mod.rs	0.00%	14 Missing ⚠️
storage/src/store/rpc/mod.rs	0.00%	10 Missing ⚠️
rpc/src/models.rs	0.00%	5 Missing ⚠️
rpc/src/config.rs	90.90%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #656      +/-   ##
==========================================
- Coverage   45.14%   44.57%   -0.57%     
==========================================
  Files         291      293       +2     
  Lines       55030    55988     +958     
  Branches    55030    55988     +958     
==========================================
+ Hits        24842    24956     +114     
- Misses      28946    29791     +845     
+ Partials     1242     1241       -1     

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