Add new Rails/JSONSymbolizeNames cop

[viralpraxis]

I've seen this pattern a lot:

JSON.parse(large_json).deep_symbolize_keys

instead of travesing Ruby hash once more we can use the symbolize_names option:

JSON.parse(large_json, symbolize_names: true)

Caveats / FP scenarios:

1. symbolize_names does not work if create_addition option is provided.
2. User might use both symbolize_names: false and deep_symbolize_keys.
3. There's no autocorrection yet, but it should be relatively easy to add (at least for some cases)

---

Before submitting the PR make sure the following are checked:

• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Wrote good commit messages.
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Ran bundle exec rake default. It executes all tests and runs RuboCop on its own code.
• Added an entry (file) to the changelog folder named {change_type}_{change_description}.md if the new code introduces user-observable changes. See changelog entry format for details.

[koic]

Could you first propose this style to the style guide?
https://github.com/rubocop/rails-style-guide

[koic]

This message only shows the option name, which might make it difficult for users to understand the expected action in their code. It may be simpler to provide autocorrection and show the corrected code instead.

[viralpraxis]

I've implemented autocorrection

[viralpraxis]

Could you first propose this style to the style guide? https://github.com/rubocop/rails-style-guide

From the issue:

As a cop - certainly yes. As a guideline - I’m uncertain if it’s worth it.

So seems like this cop is acceptable, could you please take a look? @koic

[viralpraxis]

Pinging since there's no activity for 2 months @koic

Can we either close or merge it?

[koic]

It follows the direction of rubocop/rails-style-guide#372, and since progress on the style guide has stalled, this PR has also been on hold.