Support whole word transform on tabstop and variable

[MunifTanjim]

• Add missing /camelcase and /pascalcase from the Grammar.
• Support whole word transform
  • supported regex: (.*) (i.e. the whole word)
  • supported formats: '/upcase' | '/downcase' | '/capitalize' | '/camelcase' | '/pascalcase'

Related to: https://github.com/hrsh7th/vim-vsnip/issues/83#issuecomment-856075164 https://github.com/hrsh7th/vim-vsnip/issues/209

This helps with my React.js snippet;

{
  "useState": {
    "prefix": "us",
    "body": "const [${1:state}, set${1/(.*)/${1:/capitalize}/}] = useState(${2:initial${1/(.*)/${1:/capitalize}/}})$0",
    "description": "hook: useState"
  }
}

[hrsh7th]

This approach is good to me. I'll review it.

[hrsh7th]

LGTM! Do you have remaining todo for this?

[MunifTanjim]

Do you have remaining todo for this?

Nope, that's it for now.

[hrsh7th]

Thank you for your contribution!