Make OTA function switchable in web_server component (#2685)

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>

tests/test1.yaml

@@ -234,6 +234,7 @@ logger:
 
 web_server:
   port: 8080
+  ota: true
   css_url: https://esphome.io/_static/webserver-v1.min.css
   js_url: https://esphome.io/_static/webserver-v1.min.js
 

tests/test4.yaml

@@ -45,6 +45,7 @@ logger:
   level: DEBUG
 
 web_server:
+  ota: false
   auth:
     username: admin
     password: admin