commands/new: Embed site and theme skeletons

The skeletons are used when creating new sites and themes with the CLI.

Closes #11358

create/skeletons/theme/theme.toml

@@ -0,0 +1,31 @@
+name = 'Theme name'
+license = 'MIT'
+licenselink = 'https://github.com/owner/repo/LICENSE'
+description = 'Theme description'
+
+# The home page of the theme, where the source can be found
+homepage = 'https://github.com/owner/repo'
+
+# If you have a running demo of the theme
+demosite = 'https://owner.github.io/repo'
+
+# Taxonomy terms
+tags = ['blog', 'company']
+features = ['some', 'awesome', 'features']
+
+# If the theme has multiple authors
+authors = [
+  {name = 'Name of author', homepage = 'Website of author'},
+  {name = 'Name of author', homepage = 'Website of author'}
+]
+
+# If the theme has a single author
+[author]
+  name = 'Your name'
+  homepage = 'Your website'
+
+# If porting an existing theme
+[original]
+  author = 'Name of original author'
+  homepage = 'Website of original author'
+  repo = 'https://github.com/owner/repo'