Force the entire KC string to match shiftedKcRegExp

This is useful to avoid false positives like "RCTL(S(KC_A))".

src/i18n/keymap_extras/convert_keymap_extras_header.js

@@ -172,7 +172,7 @@ function computeKcInfo(lines, intl2us) {
       keysym: readableKeysym,
       name: readableKeysym
     });
-    const shiftedKcRegExp = /S\(\w+\)/;
+    const shiftedKcRegExp = /^S\(\w+\)$/;
     if (shiftedKcRegExp.test(macroExpansion)) {
       const basicKc = extractBasicKc(macroExpansion);
       const basicUSKc = translateToUS(basicKc, intl2us);