Renamed the electrs backend support to 'electrs'.

frontend/src/environments/environment-electrs.prod.ts

@@ -1,4 +1,4 @@
 export const environment = {
   production: true,
-  esplora: true,
+  electrs: true,
 };

frontend/src/environments/environment.prod.ts

@@ -1,4 +1,4 @@
 export const environment = {
   production: true,
-  esplora: false,
+  electrs: false,
 };

frontend/src/environments/environment.ts

@@ -4,7 +4,7 @@
 
 export const environment = {
   production: false,
-  esplora: true,
+  electrs: true,
 };
 
 /*