refactor(scss): properly prefix string imports (#29987)

Author: brandyscarney

core/src/components/item/item.common.scss

@@ -1,4 +1,3 @@
-@import "../../themes/functions.string";
 @import "../../themes/mixins";
 
 // Item

core/src/components/radio/radio.common.scss

@@ -1,4 +1,3 @@
-@import "../../themes/functions.string";
 @import "../../themes/mixins";
 @import "./radio.vars.scss";
 

core/src/components/segment-button/segment-button.common.scss

@@ -1,4 +1,3 @@
-@import "../../themes/functions.string";
 @import "../../themes/mixins";
 
 // Segment Button: Common

core/src/components/spinner/spinner.common.scss

@@ -1,6 +1,6 @@
-@import "../../themes/functions.string";
-@import "../../themes/functions.color";
 @import "../../themes/mixins";
+// Required to use the current-color function
+@import "../../themes/functions.color";
 
 // Spinners
 // --------------------------------------------------

core/src/components/toast/toast.common.scss

@@ -1,6 +1,5 @@
 @import "../../themes/mixins";
-// Necessary for the mixins to work.
-@import "../../themes/functions.string";
+// Required to use the current-color function
 @import "../../themes/functions.color";
 
 // Toast

core/src/themes/mixins.scss

@@ -309,7 +309,7 @@
 // ----------------------------------------------------------
 @mixin svg-background-image($svg, $flip-rtl: false) {
   $url: url-encode($svg);
-  $viewBox: str-split(str-extract($svg, "viewBox='", "'"), " ");
+  $viewBox: string.str-split(string.str-extract($svg, "viewBox='", "'"), " ");
 
   @if $flip-rtl != true or $viewBox == null {
     @include multi-dir() {
@@ -318,9 +318,9 @@
   } @else {
     $transform: "transform='translate(#{nth($viewBox, 3)}, 0) scale(-1, 1)'";
     $flipped-url: $svg;
-    $flipped-url: str-replace($flipped-url, "<path", "<path #{$transform}");
-    $flipped-url: str-replace($flipped-url, "<line", "<line #{$transform}");
-    $flipped-url: str-replace($flipped-url, "<polygon", "<polygon #{$transform}");
+    $flipped-url: string.str-replace($flipped-url, "<path", "<path #{$transform}");
+    $flipped-url: string.str-replace($flipped-url, "<line", "<line #{$transform}");
+    $flipped-url: string.str-replace($flipped-url, "<polygon", "<polygon #{$transform}");
     $flipped-url: url-encode($flipped-url);
 
     @include ltr() {
@@ -575,10 +575,10 @@
 
   @each $transform in $transforms {
     @if (str-index($transform, translate3d)) {
-      $transform: str-replace($transform, "translate3d(");
-      $transform: str-replace($transform, ")");
+      $transform: string.str-replace($transform, "translate3d(");
+      $transform: string.str-replace($transform, ")");
 
-      $coordinates: str-split($transform, ",");
+      $coordinates: string.str-split($transform, ",");
 
       $x: nth($coordinates, 1);
       $y: nth($coordinates, 2);