chore: Rename composer package and fix workflow for main

[colinmurphy]

Description

1. Renames our composer package to composer-packages.json instead of package.json (thanks @theodesp for pointing this out that it is like npm package file name)
2. Fixes issues with failing workflows when a branch is merged into main as it has no base sha for the pull request. This has a knock on effect of making our badges for plugins fail.
3. Fixes workflows for code quality etc to run off plugin sub-directory changes not plugin changes e.g. plugins/composer-packages.json should not trigger a e2e test workflow.

Related Issue

#303

Dependant PRs

Type of Change

• ✅ Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactoring (no functional changes)
• 📄 Example update (no functional changes)
• 📝 Documentation update
• 🔍 Performance improvement
• 🧪 Test update

How Has This Been Tested?

Screenshots

Checklist

• I have read the CONTRIBUTING document
• My code follows the project's coding standards
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works (if applicable)
• Any dependent changes have been highlighted, merged or published

[changeset-bot]

⚠️ No Changeset found

Latest commit: bb3bb2e

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[github-actions]

ℹ️ Download the latest hwp-previews plugin zip from this PR
(See the 'Artifacts' section at the bottom)