[Intl] Skip tests that need full lib-intl when there's no lib-intl

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | 
| License       | MIT
| Doc PR        | 

`NumberFormatter::formatCurrency` executes indirectly `Symfony\Component\Intl\ResourceBundle\Reader::read()`, which has `$bundle = new \ResourceBundle($locale, $path)` - there's Fatal Error if `\ResourceBundle` isn't found. Added availability to run unit tests if `lib-intl` isn't installed.