ORC-720: Run mvn checkstyle:check in GitHub action.

[williamhyun]

What changes were proposed in this pull request?

This PR aims to run mvn checkstyle:check in GitHub action.

Why are the changes needed?

This will enforce the coding style before merging.

How was this patch tested?

Manually, check the GitHub action log in this PR.

[dongjoon-hyun]

+1, LGTM. (Pending CIs)
Nice! I agree that this is helpful for review process.

[dongjoon-hyun]

From the GitHub Action log, I verified the following.

2482 [INFO] --- maven-checkstyle-plugin:3.1.1:check (default-cli) @ orc-examples ---
2483
[INFO] You have 0 Checkstyle violations.
2484
[INFO] ------------------------------------------------------------------------
2485
[INFO] Reactor Summary for Apache ORC 1.7.0-SNAPSHOT:
2486
[INFO] 
2487
[INFO] Apache ORC ......................................... SUCCESS [  3.336 s]
2488
[INFO] ORC Shims .......................................... SUCCESS [  0.053 s]
2489
[INFO] ORC Core ........................................... SUCCESS [  0.135 s]
2490
[INFO] ORC MapReduce ...................................... SUCCESS [  0.034 s]
2491
[INFO] ORC Tools .......................................... SUCCESS [  0.046 s]
2492
[INFO] ORC Examples ....................................... SUCCESS [  0.023 s]
2493
[INFO] ------------------------------------------------------------------------
2494
[INFO] BUILD SUCCESS
2495
[INFO] ------------------------------------------------------------------------
2496
[INFO] Total time:  4.059 s
2497
[INFO] Finished at: 2021-01-09T20:08:53Z
2498
[INFO] ------------------------------------------------------------------------

[dongjoon-hyun]

This is merged via d741a36

[dongjoon-hyun]

While you are working on this, could you make an umbrella JIRA and put your subtask JIRAs under that JIRA, please?

[williamhyun]

Sure I will create an umbrella JIRA @dongjoon-hyun.