[Icons] Update FormMajor icon (#7686)

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### WHY are these changes introduced?
Implementing final changes to Shopify Forms icon to align with all
global surfaces affiliated with Shopify Forms, including in Admin and
marketing materials.

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  Context about the problem that’s being addressed.
-->

### WHAT is this pull request doing?
Replaces the old FormMajor svg with a new svg and updates the
FormMajor.yml file with new version number and `date_modified` date.

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### 🎩 checklist

- [ ] Tested on
[mobile](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting.md#cross-browser-testing)
- [x] Tested on [multiple
browsers](https://help.shopify.com/en/manual/shopify-admin/supported-browsers)
- [ ] Tested for
[accessibility](https://github.com/Shopify/polaris/blob/main/documentation/Accessibility%20testing.md)
- [x] Updated the component's `README.md` with documentation changes
- [x] [Tophatted
documentation](https://github.com/Shopify/polaris/blob/main/documentation/Tophatting%20documentation.md)
changes in the style guide

Author: matyikriszta

.changeset/fresh-tigers-cross.md

@@ -0,0 +1,5 @@
+---
+'@shopify/polaris-icons': minor
+---
+
+Update FormMajor icon

polaris-icons/icons/FormsMajor.svg

@@ -7,7 +7,7 @@ keywords:
   - text
 authors:
   - Adam Whitcroft
-version: 1
+version: 2
 date_added: 2019-03-15
-date_modified: 2019-03-15
+date_modified: 2022-11-07
 exclusive_use: