[types] Some useful function for type convert and add get_state_node_by_node_hash to RPCClient

[strawWoo]

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the new behavior?

add some rpc-api and convert to help mini-starcoin

[codecov]

Codecov Report

Merging #3643 (6578a5b) into master (95e146e) will decrease coverage by 0.82%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #3643      +/-   ##
==========================================
- Coverage   28.69%   27.87%   -0.81%     
==========================================
  Files         591      591              
  Lines       50640    50691      +51     
  Branches    23868    23886      +18     
==========================================
- Hits        14525    14124     -401     
- Misses      21923    22629     +706     
+ Partials    14192    13938     -254     

Flag	Coverage Δ
unittests	27.87% <0.00%> (-0.81%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
rpc/api/src/types.rs	5.26% <0.00%> (-8.46%)	⬇️
rpc/client/src/lib.rs	0.36% <0.00%> (-10.77%)	⬇️
rpc/api/src/metadata.rs	36.37% <0.00%> (-45.45%)	⬇️
types/src/lib.rs	9.10% <0.00%> (-36.36%)	⬇️
rpc/api/src/node/mod.rs	10.53% <0.00%> (-31.57%)	⬇️
rpc/client/src/chain_watcher.rs	0.00% <0.00%> (-26.50%)	⬇️
rpc/client/src/pubsub_client.rs	0.00% <0.00%> (-25.71%)	⬇️
rpc/client/src/remote_state_reader.rs	0.00% <0.00%> (-20.37%)	⬇️
rpc/api/src/account/mod.rs	7.15% <0.00%> (-17.85%)	⬇️
rpc/server/src/module/mod.rs	0.00% <0.00%> (-16.66%)	⬇️
... and 92 more

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