Prior to this commit, the auto-configuration was scanning for
`"*.graphql,*.gql,*.graphqls,*.gqls"` files in the configured locations.
This was not flexible enough, as developers could not customize the
considered file extensions when scanning for files.
This commit provides a new `spring.graphql.schema.file-extensions`
configuration property that enables such customizations.
Because `"*.graphql,*.gql"` extensions seem to be tied to queries
(and not schemas), this commit also changes the default value to only
consider the `"*.graphqls,*.gqls"` file extensions by default.
Closes gh-134
Closes gh-135
f69aa39211