[dev]: Update PR template for danger checks (and update danger)

[sirugh]

Description

Adding some tooling around the contents of PR as in the labels, description, etc:

• Made some small changes to the PR template.
• Updated dangerfile for checking PR labels, description and other rules we want to apply to the pull request metadata rather than the code changes.
• Trigger that job hourly since AWS CodeBuild doesn't allow usage of Github's PR Edit webhooks (currently they only have create/update/reopen).

Related Issue

Closes #1279 .

Verification Steps

1. Check out the PR and yarn install.
2. Run danger pr https://github.com/magento-research/pwa-studio/pull/1269 or replace the PR link with some other PR you want to test.
3. See results in your console.
4. To test each failure, open your own PR and:

• Add a TODO in the description somewhere
• Delete a section header completely.
• Leave one of the sections as the default text like Closes #<ISSUE_NUMBER>.
• After the above, replace #ISSUE_NUMBER with a closed issue.
• Do not apply a version label.
• Check that appropriate project labels are applied (should apply on changes to code within the packages directories.

How have YOU tested this?

Tested locally with danger pr https://github.com/magento-research/pwa-studio/pull/1269

Proposed Labels for Change Type/Package

• major (e.g x.0.0 - a breaking change)
• minor (e.g 0.x.0 - a backwards compatible addition)
• patch (e.g 0.0.x - a bug fix)

Checklist:

• I have updated the documentation accordingly, if necessary.
• I have added tests to cover my changes, if necessary.

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