refactor into <lnbits-footer /> component (#3487)

lnbits/static/js/components/lnbits-footer.js

@@ -0,0 +1,18 @@
+window.app.component('lnbits-footer', {
+  template: '#lnbits-footer',
+  mixins: [window.windowMixin],
+  computed: {
+    version() {
+      return this.LNBITS_VERSION || 'unknown version'
+    },
+    title() {
+      return `${this.SITE_TITLE}, ${this.SITE_TAGLINE}`
+    },
+    showFooter() {
+      return (
+        this.SITE_TITLE == 'LNbits' &&
+        this.LNBITS_SHOW_HOME_PAGE_ELEMENTS == true
+      )
+    }
+  }
+})