typo in the JSONObject method name: forEchArrayObject -> forEachArrayObject

[olafmat]

What this PR does / why we need it?

It's just fixing of a method name which contained a type. The backward compatibility is preserved.

Summary of your change

This PR changes method name forEchArrayObject to forEachArrayObject because it contained a typo.
The previous method is left for compatibility, but marked as deprecated.

The method was not used in the tests or documentation.

Please indicate you've done the following:

• Made sure tests are passing and test coverage is added if needed.
• Made sure commit message follow the rule of Conventional Commits specification.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed.

[CLAassistant]

All committers have signed the CLA.

[wenshao]

fastjson2需要兼容JDK8，你提交的代码无法在JDK8下构建通过

[olafmat]

Sorry. It's already fixed, the code is compatible with JDK 8 now.