fix: provider api

[yqrashawn]

1. fix broken sendAsync
2. support provider.on('data')

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This change is 

[codecov]

Codecov Report

Merging #1003 (d39b4a6) into dev (39c9917) will increase coverage by 12.88%.
The diff coverage is 25.00%.

@@             Coverage Diff             @@
##              dev    #1003       +/-   ##
===========================================
+ Coverage   27.25%   40.13%   +12.88%     
===========================================
  Files         563      563               
  Lines       33442    33445        +3     
  Branches     1253     1918      +665     
===========================================
+ Hits         9115    13424     +4309     
+ Misses      24148    19838     -4310     
- Partials      179      183        +4     

Flag	Coverage Δ
integrationtests	31.89% <0.00%> (?)
unittests	27.25% <25.00%> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
packages/ui/provider-api/Provider.js	41.17% <25.00%> (-0.12%)	⬇️
packages/rpc-engine/src/error.js	79.66% <0.00%> (+3.38%)	⬆️
...ackages/rpcs/cfx_estimateGasAndCollateral/index.js	100.00% <0.00%> (+3.63%)	⬆️
packages/rpcs/wallet_getAccountGroup/index.js	94.28% <0.00%> (+4.28%)	⬆️
packages/webextension/popup.js	21.08% <0.00%> (+5.42%)	⬆️
packages/signature/index.js	70.29% <0.00%> (+5.44%)	⬆️
packages/rpcs/cfx_gasPrice/index.js	46.15% <0.00%> (+5.76%)	⬆️
packages/json-rpc-error/index.js	80.53% <0.00%> (+8.05%)	⬆️
packages/rpc-engine/src/permissions.js	100.00% <0.00%> (+8.33%)	⬆️
packages/rpcs/cfx_call/index.js	100.00% <0.00%> (+8.51%)	⬆️
... and 88 more

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