Process files with netlify (#1841)

I'm not sure if this will actually work, but if it does, it'll reduce
the size of a bunch of the image files automatically & not require us to
worry about that anymore.

It'll also combine all our JS & CSS files into a single bundled request.

netlify.toml

@@ -3,6 +3,18 @@
   command = "make netlify"
   environment = { BASE_URL = "https://esphome.io" }
 
+[build.processing]
+  # only size-minimize everything in production
+  skip_processing = true
+[build.processing.css]
+  bundle = true
+  minify = true
+[build.processing.js]
+  bundle = true
+  minify = true
+[build.processing.images]
+  compress = true
+
 [context.beta]
   environment = { BASE_URL = "https://beta.esphome.io" }
 
@@ -11,6 +23,8 @@
 
 [context.production]
   environment = { BASE_URL = "https://esphome.io", PRODUCTION = "YES" }
+[context.production.processing]
+  skip_processing = false
 
 # A basic redirect rule
 [[redirects]]