add eslint and prettier and apply

[ananzh]

Description

• add prettier and apply prettier
• add eslint and its config; apply eslint
• modify package.json script
• turn off no-unused-vars and no-dupe-else-if. will fix them in separate PRs
• modify workflow to run yarn lint for restricter format check
• remove standard

Issue Resolved:

#243

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[ananzh]

unit and integration:

yarn test:unit
yarn run v1.22.5
$ tap test/unit/{*,**/*}.test.js
 RUNS  test/unit/api.test.js 217ms
 RUNS  test/unit/api.test.js 265ms
 SKIP  test/unit/esm/index.test.js
 ~ Skip because Node version < 12.17.0

 RUNS  test/unit/api.test.js 365ms
 SKIP  test/unit/esm/index.test.js 1 skip of 1 3.425ms
 ~ Skip because Node version < 12.17.0

 PASS  test/unit/selectors.test.js 8 OK 9.563ms
 PASS  test/unit/cloud-connection-pool.test.js 4 OK 14.875ms
 PASS  test/unit/helpers/search.test.js 8 OK 25.07ms
 PASS  test/unit/events.test.js 19 OK 33.283ms
 PASS  test/unit/errors.test.js 36 OK 29.342ms
 PASS  test/unit/api.test.js 25 OK 73.62ms
 PASS  test/unit/serializer.test.js 19 OK 33.465ms
 PASS  test/unit/base-connection-pool.test.js 44 OK 88.767ms
 PASS  test/unit/connection-pool.test.js 89 OK 168.016ms
 PASS  test/unit/child.test.js 36 OK 151.196ms
test/unit/helpers/bulk.test.js 2> (node:358889) DeprecationWarning: strictEqual() is deprecated, use equal() instead
test/unit/helpers/bulk.test.js 2> (node:358889) DeprecationWarning: deepEqual() is deprecated, use same() instead
 PASS  test/unit/helpers/scroll.test.js 58 OK 189.959ms
 PASS  test/unit/helpers/bulk.test.js 291 OK 244.887ms
 PASS  test/unit/helpers/msearch.test.js 49 OK 567.967ms
 PASS  test/unit/connection.test.js 73 OK 3s
 PASS  test/unit/transport.test.js 202 OK 4s
 PASS  test/unit/client.test.js 116 OK 11s

                         
  🌈 SUMMARY RESULTS 🌈  
                         

 SKIP  test/unit/esm/index.test.js 1 skip of 1 3.425ms
 ~ Skip because Node version < 12.17.0

Suites:   17 passed, 17 of 17 completed
Asserts:  1077 passed, 1 skip, of 1078
Time:     12s
Done in 12.34s.


yarn test:integration:helpers
yarn run v1.22.5
$ tap test/integration/helpers/*.test.js
 PASS  test/integration/helpers/search.test.js 11 OK 2s
 PASS  test/integration/helpers/msearch.test.js 27 OK 6s
 PASS  test/integration/helpers/scroll.test.js 215 OK 6s
 PASS  test/integration/helpers/bulk.test.js 25 OK 8s

                         
  🌈 SUMMARY RESULTS 🌈  
                         

Suites:   4 passed, 4 of 4 completed
Asserts:  278 passed, of 278
Time:     8s
Done in 8.71s.

[ananzh]

sanity test:

node data.js
Creating index:
{ acknowledged: true, shards_acknowledged: true, index: 'books' }
Cluster health:
{ cluster_name: 'runTask',
  status: 'yellow',
  timed_out: false,
  number_of_nodes: 1,
  number_of_data_nodes: 1,
  discovered_master: true,
  discovered_cluster_manager: true,
  active_primary_shards: 4,
  active_shards: 4,
  relocating_shards: 0,
  initializing_shards: 0,
  unassigned_shards: 12,
  delayed_unassigned_shards: 0,
  number_of_pending_tasks: 0,
  number_of_in_flight_fetch: 0,
  task_max_waiting_in_queue_millis: 0,
  active_shards_percent_as_number: 25 }
Cluster getSettings use master_timeout:
{ persistent: {}, transient: {} }
Cluster getSettings use cluster_manager_timeout:
{ persistent: {}, transient: {} }
Adding document:
{ _index: 'books',
  _id: '1',
  _version: 1,
  result: 'created',
  forced_refresh: true,
  _shards: { total: 4, successful: 1, failed: 0 },
  _seq_no: 0,
  _primary_term: 1 }
Search results:
{ total: { value: 1, relation: 'eq' },
  max_score: 0.5753642,
  hits:
   [ { _index: 'books',
       _id: '1',
       _score: 0.5753642,
       _source: [Object] } ] }
Deleting document:
{ _index: 'books',
  _id: '1',
  _version: 2,
  result: 'deleted',
  _shards: { total: 4, successful: 1, failed: 0 },
  _seq_no: 1,
  _primary_term: 1 }
Deleting index:
{ acknowledged: true }