test: [Snaps E2E] Create test for Signature Insights (#23133)

## **Description**

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also include relevant motivation and context. Have in mind the following
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This creates a test for Signature Insights via snaps.

[![Open in GitHub
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## **Related issues**

Fixes:
[#22785](#22785)

## **Manual testing steps**

1. Run E2E test locally

## **Screenshots/Recordings**

<!-- If applicable, add screenshots and/or recordings to visualize the
before and after of your change. -->

### **Before**

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### **After**

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## **Pre-merge author checklist**

- [x] I’ve followed [MetaMask Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've clearly explained what problem this PR is solving and how it
is solved.
- [x] I've linked related issues
- [ ] I've included manual testing steps
- [ ] I've included screenshots/recordings if applicable
- [x] I’ve included tests if applicable
- [ ] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [ ] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.
- [x] I’ve properly set the pull request status:
  - [ ] In case it's not yet "ready for review", I've set it to "draft".
- [ ] In case it's "ready for review", I've changed it from "draft" to
"non-draft".

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

---------

Co-authored-by: Hassan Malik <41640681+hmalik88@users.noreply.github.com>

Author: bowensanders

test/e2e/run-all.js

@@ -12,6 +12,7 @@ const FLASK_ONLY_TESTS = [
   'test-snap-txinsights-v2.spec.js',
   'test-snap-namelookup.spec.js',
   'test-snap-homepage.spec.js',
+  'test-snap-siginsights.spec.js',
 ];
 
 const getTestPathsForTestDir = async (testDir) => {