[JS] Define code entry point for integration testing

[asfimport]

This needs to provide a similar command line interface to the Java and C++ integration testing entry points:

• Command: convert JSON to Arrow, or Arrow to JSON
• Arrow file path
• JSON file path

Reporter: Wes McKinney / @wesm

Related issues:

• [JS] JavaScript integration tests (is part of)
• [JS] Integrate auto-generated Arrow test files (is depended upon by)

_{Note: This issue was originally created as ARROW-1502. Please see the migration documentation for further details.}

[asfimport]

Paul Taylor / @trxcllnt:
resolved in #1482