#1333 | Interface for MetadataDiff

[shraddha761]

Issue -> #1333

[himeshr]

Make MetadataDiff methods renderJsonWithColor() and filterForms() easier to understand:

• breaking into smaller methods
• having self-explanatory method names for smaller methods
• Create constants with explanatory names for conditions used in render method
  Ex: const areFilesMissing = (missingFilesNode) => {... some condition}

[1t5j0y]

Refactoring looks good.

Few more comments:

• Remove the typeof checks and use lodash (look for usages in the current code) methods like isNil, isEmpty to check for null, undefined, empty etc
• Use constants for possible values of changeType