Update to use polaris-icons v2

[BPScott]

WHY are these changes introduced?

This adds treeshaking support, esm builds and has renamed the exports.

WHAT is this pull request doing?

• Update to @shopify/polaris-icons v2.0.0
• Update imports to reflect new export names

Note that the names you put into Icon source remain unaffected - you'd still do <Icon source="add">, but that now add maps to the named export addMinor.

How to 🎩

• Assert percy passes (and thus icons still render)
• Assert build passes (and thus there's no incorrect imports)

[BPScott]

This whole file could all be replaced with just export * from '@shopify/polaris-icons' but IIRC @amrocha and I decided that it's best to be explicit.

I'm still kinda tempted to 🔥 this file entirely and just import icons direct within the Icon component but we can decide if we want to do that later

[amrocha]

Like we discussed, I believe having an index file creates good habits. Prune a list of icons down to the ones you need and use them, instead of potentially adding a new icon every time

On the export * side though, I talked to Kaelig and it sounds like there's only a few icons that are problematic, so I'm gonna put something together soon, run it by Jesse and see if we can get it merged. If we do then what I said above doesn't apply anymore and we can get rid of this file

[amrocha]

Like we discussed, I believe having an index file creates good habits. Prune a list of icons down to the ones you need and use them, instead of potentially adding a new icon every time

On the export * side though, I talked to Kaelig and it sounds like there's only a few icons that are problematic, so I'm gonna put something together soon, run it by Jesse and see if we can get it merged. If we do then what I said above doesn't apply anymore and we can get rid of this file