feat: Support dark mode in login pages (#7420)

Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

app/javascript/v3/views/auth/signup/components/AuthSubmitButton.vue

@@ -0,0 +1,55 @@
+<template>
+  <woot-button
+    size="expanded"
+    color-scheme="primary"
+    class-names="submit--button"
+    :is-disabled="isDisabled"
+    :is-loading="isLoading"
+    @click="onClick"
+  >
+    {{ label }}
+    <fluent-icon :icon="icon" size="18" />
+  </woot-button>
+</template>
+
+<script>
+export default {
+  props: {
+    label: {
+      type: String,
+      default: '',
+    },
+    icon: {
+      type: String,
+      default: '',
+    },
+    isDisabled: {
+      type: Boolean,
+      default: false,
+    },
+    isLoading: {
+      type: Boolean,
+      default: false,
+    },
+  },
+  methods: {
+    onClick() {
+      this.$emit('click');
+    },
+  },
+};
+</script>
+
+<style lang="scss" scoped>
+.submit--button {
+  align-items: center;
+  display: flex;
+  margin: 0 0 var(--space-normal) 0;
+
+  &::v-deep .button__content {
+    align-items: center;
+    display: flex;
+    justify-content: center;
+  }
+}
+</style>