return eth tx hash to client

[yihuang]

Closes #67

Description

• SendTransaction return eth tx hash to client
• GetTransaction convert eth hash to tm hash by calling /tx_search.
• Use eth tx hash internally

Verified in external integration test:

    signed = eth_account.Account.sign_transaction(tx, VALIDATOR_PRIV_KEY)
    txhash = w3.eth.sendRawTransaction(signed.rawTransaction)
    assert txhash == signed.hash, 'invalid tx hash'
    time.sleep(5)
    tx = w3.eth.getTransactionReceipt(txhash)
    print("tx receipt", tx)

---

For contributor use:

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer

---

For admin use:

• Added appropriate labels to PR (ex. WIP, R4R, docs, etc)
• Reviewers assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[fedekunze]

Looks good. Minor suggestions only. Can you add a changelog entry and create an issue to write a test for this?

[leejw51crypto]

lgtm

[yihuang]

Looks good. Minor suggestions only. Can you add a changelog entry and create an issue to write a test for this?

done
#209

[codecov]

Codecov Report

Merging #202 (64c674d) into main (036ffb7) will increase coverage by 20.67%.
The diff coverage is 100.00%.

❗ Current head 64c674d differs from pull request most recent head e87b642. Consider uploading reports for the commit e87b642 to get more accurate results

@@             Coverage Diff             @@
##             main     #202       +/-   ##
===========================================
+ Coverage   46.90%   67.57%   +20.67%     
===========================================
  Files          43        9       -34     
  Lines        2889      808     -2081     
===========================================
- Hits         1355      546      -809     
+ Misses       1463      238     -1225     
+ Partials       71       24       -47     

Impacted Files	Coverage Δ
app/app.go	86.40% <100.00%> (-0.06%)	⬇️
types/codec.go
x/evm/types/query.pb.gw.go
types/int.go
x/evm/types/codec.go
x/evm/module.go
x/evm/types/params.go
types/config.go
types/validation.go
x/evm/keeper/abci.go
... and 21 more

[fedekunze]

@yihuang can you fix the build errors? 🙏

[yihuang]

@yihuang can you fix the build errors? 🙏

fixed and rebased.