Add LocationIQ as supported map provider (#1293)

- Add LocationIQ access token field to settings and export modals
  - Include LocationIQ Streets style in gallery
  - Support automatic token replacement for LocationIQ URLs
  - Add LocationIQ tileset configuration
  - Include translations for all supported languages

## Launch Checklist
 - [x] Briefly describe the changes in this PR.
 - [x] Write tests for all new functionality.
 - [x] Add an entry to `CHANGELOG.md` under the `## main` section.

src/libs/field-spec-additional.ts

@@ -20,6 +20,12 @@ const spec = (t: TFunction) => ({
       docUrl: "https://docs.stadiamaps.com/authentication/",
       docUrlLinkText: t("Learn More")
     },
+    locationiq_access_token: {
+      label: t("LocationIQ Access Token"),
+      doc: t("Public access token for LocationIQ services."),
+      docUrl: "https://docs.locationiq.com/docs/maps",
+      docUrlLinkText: t("Learn More")
+    },
     style_renderer: {
       label: t("Style Renderer"),
       doc: t("Choose the default Maputnik renderer for this style.")