Add in theme setting (textarea) to include additional meta data

[MiiaKlingstedt]

Additional meta data is usually needed in websites, and even though it is easy to add in the theme files, also a theme setting can make it easier to add in the content.

1. In theme settings config file settings.json add in a text area: https://cradlecms.com/blogs/webdev-guides/article/theme-settings#textarea
2. In main theme template (theme.liquid) and restricted template (restricted.liquid) files add a place in tag for the content, if there is any added in theme settings.

Example of content:

<meta name="google-site-verification" content="yrlLe9B_nsodvER9a7ReE2GODkG6XPW4OZruRA9LH5k">