Rework `DocumentLinks` to use `@shopify/theme-graph`

[aswamy]

Is your feature request related to a problem? Please describe.

Shopify/theme-graph allowed each file to be able to tell if it has a reference or dependency to another file.

Instead of explicitly looking through Liquid Tags and checking to see if it's a variable or liquid string, we can just underline all references in liquid files using theme-graph's reference.

File in question: https://github.com/Shopify/theme-tools/blob/main/packages/theme-language-server-common/src/documentLinks/DocumentLinksProvider.ts#L37-L50

• Refactor provider to include theme-graph
• Introduce document linking from Liquid schemas to blocks/sections it's referencing
• Introduce document linking from web components to the javascript file it's referencing

Describe the solution you'd like

• Ideally we can keep this file extremely minimal and only check the theme-graph for references and where it's located in the file
• Introduces schema level document linking (which currently doesn't exist)