Badgen is a faster successor of shields.io:
https://github.com/badgen/badgen.net

Backport from `master`-branch.

Fixes the following error when running integration-tests:
```
npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR!
npm ERR! While resolving: webpack-test@1.0.0
npm ERR! Found: handlebars@5.0.0-alpha.1
npm ERR! node_modules/handlebars
npm ERR!   dev handlebars@"file:../../.." from the root project
npm ERR!
npm ERR! Could not resolve dependency:
npm ERR! peer handlebars@">= 1.3.0 < 5" from handlebars-loader@1.7.1
npm ERR! node_modules/handlebars-loader
npm ERR!   dev handlebars-loader@"^1.7.1" from the root project
npm ERR!
```

As explained in issue #1844 and in issue
webpack/webpack#15007 (comment),
the way we used the `browser`-field was wrong.

The main reason for using the `browser`-field is the requirement of
`require('fs')` in the main-entry-file.
The workaround for this was using `require('handlebars/lib/handlebars')`,
but now it will also work via `require('handlebars')` for bundlers that
respect the `browser`-field.

The `"./runtime"`-config was removed, because it didn't have any effect.
In order to detect regressions, the webpack-integration test was
extended to test with different webpack versions.

Fixes #1174
Closes #1844

Fixes #1820
Closes #1821

```
npm ERR! `npm ci` can only install packages when your package.json and package-lock.json or npm-shrinkwrap.json are in sync. Please update your lock file with `npm install` before continuing.
npm ERR!
npm ERR! Invalid: lock file's acorn@5.7.4 does not satisfy acorn@7.4.1
npm ERR! Missing: acorn@5.7.4 from lock file
```

When using Handlebars in a Cloudflare Worker, an environment
in which the `window` and `global` objects both don't exist,
an error is thrown about `window` being undefined.

According to the ECMA specification, only `self` is available
in a worker. Since we support old runtimes in our 4.x branch,
we can't use `globalThis` but have to use a polyfill.

* Replaced outdated `grunt-bg-shell`-package to get rid of
  coffee-script warnings

Backports parts of 785a63e.

In order to automate publishing 4.x releases to AWS S3,
we also need this workflow on the 4.x branch.

See #1972

When visiting the www-variant, a `SSL_ERROR_INTERNAL_ERROR_ALERT`
error is displayed by the browser.

This commit backports changes from `master`.

Fixes #1838