[l10n] Add Icelandic (is-IS) locale (#19538)

Author: axelbjornsson

docs/src/pages/guides/localization/localization.md

@@ -37,6 +37,7 @@ const theme = createMuiTheme({
 | Finnish | fi-FI | `fiFI` |
 | French | fr-FR | `frFR` |
 | German | de-DE |  `deDE` |
+| Icelandic | is-IS | `isIS` |
 | Indonesian | id-ID | `idID` |
 | Italian | it-IT | `itIT` |
 | Japanese | ja-JP | `jaJP` |

packages/material-ui/src/locale/index.d.ts

@@ -9,6 +9,7 @@ export const faIR: object;
 export const fiFI: object;
 export const frFR: object;
 export const idID: object;
+export const isIS: object;
 export const itIT: object;
 export const jaJP: object;
 export const koKR: object;

packages/material-ui/src/locale/index.js

@@ -268,6 +268,31 @@ export const frFR = {
   },
 };
 
+export const isIS = {
+  props: {
+    MuiTablePagination: {
+      backIconButtonText: 'Fyrri síða',
+      labelRowsPerPage: 'Raðir á síðu:',
+      labelDisplayedRows: ({ from, to, count }) => `${from}-${to === -1 ? count : to} af ${count}`,
+      nextIconButtonText: 'Næsta síða',
+    },
+    MuiRating: {
+      getLabelText: value => `${value} ${value === 1 ? 'Stjarna' : 'Stjörnur'}`,
+      emptyLabelText: 'Tómt',
+    },
+    MuiAutocomplete: {
+      clearText: 'Hreinsa',
+      closeText: 'Loka',
+      loadingText: 'Hlaða…',
+      noOptionsText: 'Engar niðurstöður',
+      openText: 'Opna',
+    },
+    MuiAlert: {
+      closeText: 'Loka',
+    },
+  },
+};
+
 export const idID = {
   props: {
     MuiTablePagination: {