Textarea support needed to support payloadcms/plugin-seo

[thompsonsj]

https://github.com/payloadcms/plugin-seo adds localized: true to SEO collection/global fields as expected.

e.g. for a collection with localized fields, the following is included in the fields array:

{
    "name": "meta",
    "label": "SEO",
    "type": "group",
    "fields": [
      {
        "name": "overview",
        "label": "Overview",
        "type": "ui",
        "admin": {
          "components": {}
        }
      },
      {
        "name": "title",
        "type": "text",
        "localized": true,
        "admin": {
          "components": {}
        }
      },
      {
        "name": "description",
        "type": "textarea",
        "localized": true,
        "admin": {
          "components": {}
        }
      },
      {
        "name": "preview",
        "label": "Preview",
        "type": "ui",
        "admin": {
          "components": {}
        }
      }
    ]
  }

At present, textarea is not a supported field. As a result, getLocalizedFields won't pick this up:

{
    "name": "meta",
    "label": "SEO",
    "type": "group",
    "fields": [
      {
        "name": "title",
        "type": "text",
        "localized": true,
        "admin": {
          "components": {}
        }
      }
    ]
  }

Add textarea support. It should be added anyway, but this is prioritized in order to support SEO fields.