remove tildes from core/scss and icons/scss

Description

Sass-loader has deprecated the use of tilde for awhile now: https://github.com/webpack-contrib/sass-loader#resolving-import-at-rules

Angular 15 has totally stopped supporting tilde as well: https://github.com/angular/angular-cli/issues/25266#issuecomment-1562820118

This PR removes the tilde from scss files in the core and icons packages.

I have left a couple of tildes in for example the ones in the core/app and core/templates folder as these one doesn't seem to affect us. I'm guessing since they get compiled to something else before being consumed by the end user.

(edit) looks like just removing the ~ doesn't work as it can't compile the app in core/app. I have changed it to use relative paths instead.

Motivation and Context

Allows the library to be used with Angular 15+ projects

How Has This Been Tested?

Types of changes

[ ] 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)
[ ] Documentation update
[ ] Code style update (formatting, local variables)
[x] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Other... Please describe:

Checklist:

[x] My code follows the code style of this project.
[ ] My change requires a change to the documentation.
[x] I have updated the documentation accordingly.
[x] I have read the CONTRIBUTING document.
[x] I have added tests to cover my changes.
[x] All new and existing tests passed.

Codecov Report

Patch coverage has no change and project coverage change: -0.20 :warning:

Comparison is base (80e95f9) 94.00% compared to head (4b10633) 93.81%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1454 +/- ## ========================================== - Coverage 94.00% 93.81% -0.20% ========================================== Files 132 132 Lines 18320 18320 Branches 2814 2809 -5 ========================================== - Hits 17222 17186 -36 - Misses 1098 1134 +36 ``` [see 10 files with indirect coverage changes](https://app.codecov.io/gh/momentum-design/momentum-ui/pull/1454/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=momentum-design)

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momentum-design / momentum-ui