scss Variables with path and typo3/cms-composer-installers >= 4

# Bug Report

## Prerequisites

* [x] Can you reproduce the problem on TYPO3 v11.5 LTS
* [x] Can you reproduce the problem on TYPO3 v12.4 LTS
* [x] Did you [perform a cursory search](https://github.com/issues?q=is%3Aissue+user%3Abenjaminkott+repo%3Abenjaminkott%2Fbootstrap_package)
to see if your bug or enhancement is already reported?

## Description
From cms-composer-installers >= 4 public assets will be stored in _assets Folder. If you set Paths in scss Variable it didn't work anymore.

` $icon-path: "/typ3conf/ext/sitepackage/Resources/Public/Icons"; `

$icon-path: "EXT:sitepackage/Resources/Public/Icons"; could work if it resolved to the current Path in assets Folder.
I think one of the Points to do this could be the TypoScript CompilerService.

```
if (strpos($value, 'EXT:') === 0) {
$publicResourcePath = PathUtility::getPublicResourceWebPath($value);
$value = PathUtility::getCanonicalPath($publicResourcePath);
}
```

[A clear and concise description of what the bug is.]

## Steps to Reproduce

1. [First Step]
2. [Second Step]
3. [and so on...]

### Expected behavior

[What you expected to happen]

### Actual behavior

[What actually happened]

### Screenshots

[If applicable, add screenshots to help explain your problem.]

## Versions

You can get this information from executing `composer show` at the command line
if your TYPO3 installation is composer based, otherwise the version number will
be shown in the extension manager.

Start with the TypoScript CompilerService and the PathUtility calls shown in the report, then trace how SCSS variable paths are handled after cms-composer-installers stores public assets in _assets. Reproduce the issue using the two example $icon-path values. Done means an EXT:sitepackage path resolves to the corresponding current public asset path.

Written by the indexing model from the issue text.