add GetContractDesc method

[godeamon]

Description

添加根据合约名字查询合约信息接口

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

Brief of your solution

state 增加接口，contract_info 增加接口

[codecov-commenter]

Codecov Report

Merging #364 (6ca3b5f) into master (27a54ac) will decrease coverage by 0.15%. The diff coverage is 8.33%.

@@            Coverage Diff             @@
##           master     #364      +/-   ##
==========================================
- Coverage   45.41%   45.26%   -0.16%     
==========================================
  Files         142      142              
  Lines       12460    12481      +21     
==========================================
- Hits         5659     5649      -10     
- Misses       5643     5672      +29     
- Partials     1158     1160       +2     

Impacted Files	Coverage Δ
bcs/ledger/xledger/state/state.go	46.68% <0.00%> (-0.59%)	:arrow_down:
bcs/ledger/xledger/state/tx_verification.go	14.26% <0.00%> (-0.13%)	:arrow_down:
kernel/engines/xuperos/chain.go	47.01% <28.57%> (-0.75%)	:arrow_down:
bcs/network/p2pv1/conn.go	55.10% <0.00%> (-6.13%)	:arrow_down:
bcs/consensus/tdpos/tdpos.go	47.88% <0.00%> (-0.94%)	:arrow_down:
kernel/consensus/base/driver/chained-bft/smr.go	40.59% <0.00%> (-0.75%)	:arrow_down:

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