feat: support optionalChaining & nullishCoalscingOperator

[jellydn]

WHAT

• Support optionalChaining & nullishCoalscingOperator

WHY

• Try to resolve this error

  SyntaxError: This experimental syntax requires enabling the parser plugin: 'optionalChaining' (10:46)
  at Object.raise (/Users/huynhducdung/.config/yarn/global/node_modules/js2flowchart/dist/js2flowchart.js:1:210466)

HOW

• Add to AST Parser

'optionalChaining',
'nullishCoalescingOperator'

Screenshots (if appropriate):

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] Linter
• [x] Tests
• [ ] Review comments
• [ ] Security

[jellydn]

Hi, @Bogdan-Lyashenko Thank you for your awesome work. Could you take a look at my pull request?

[Bogdan-Lyashenko]

Hi, awesome job @jellydn, thanks!