Stylelint & rules upgrade required

### Issue type

* [ ] bug report
* [X] feature request
* [ ] question about the decisions made in the repository

### Issue description

**Current behavior:**
Actually `Stylelint` version is very old (installed: `v7` VS current: `v14`).
It is also configured *without* extending the `stylelint-config-standard-scss` ruleset. This may lead to unexpected syntax and/or style behavior.
If one decides to include the `stylelint-config-standard-scss` in the project, then many errors arise, due to the syntax being arbitrary, and not compliant with (s)css standards.
This leads also to `husky` blocking the commit.

**Expected behavior:**
It's a good practice to have libraries updated to the latest compatible version, especially with CSS, where latest browser compatibility is a requirement.
Extending a standard (or recommended) rule set, is the best way to write good code, and spot possible errors.

To do so, including `stylelint-config-standard-scss` in the project, and running `lint:styles` should finish without any error.
Commits shouldn't be blocked by `husky`, due to style errors.

**Steps to reproduce:**
1. upgrade `stylelint` to the latest version: `npm i stylelint@latest --save-dev`
2. install the standard scss rule-set: `npm i stylelint-config-standard-scss --save-dev`
3. load the rules in the existing `.stylelintrc.json` by adding: `"extends": "stylelint-config-standard-scss"`
4. finally run the style lint script: `npm run lint:styles`

**Related code:**

There are many errors like the following:
```bash
src/app/pages/ui-features/typography/typography.component.scss
34:3 ✖ Expected selector ".header" to come before selector ".font-row .header" no-descending-specificity
34:3 ✖ Expected selector ".header" to come before selector ".headings-card .header" no-descending-specificity
34:3 ✖ Expected selector ".header" to come before selector ".headings-card .header:last-child" no-descending-specificity
42:5 ✖ Expected selector ".header:last-child" to come before selector ".headings-card .header:last-child" no-descending-specificity
98:5 ✖ Expected selector ".colors h1" to come before selector ".header div:first-child h1" no-descending-specificity
98:9 ✖ Expected selector ".colors h2" to come before selector ".header div:first-child h2" no-descending-specificity
98:13 ✖ Expected selector ".colors h3" to come before selector ".header div:first-child h3" no-descending-specificity
98:17 ✖ Expected selector ".colors h4" to come before selector ".header div:first-child h4" no-descending-specificity
98:21 ✖ Expected selector ".colors h5" to come before selector ".header div:first-child h5" no-descending-specificity
98:25 ✖ Expected selector ".colors h6" to come before selector ".header div:first-child h6" no-descending-specificity
```

### Other information:
```
node: v14.7.3
npm: 8.3.0
```

**Angular, Nebular**
```
angular: ~12.1.0
nebular: 8.0.0
```