Rename locale to site on redirects table

[vluijkx]

Advantages:

• More consistent with statamic/eloquent-driver.
• Fixes issue where eloquent-redirect could not be created because of validation rule in blueprint which queries based on a site column.
• Fixes issue when using eloquent redirects with multisite. The multisite filter on the index-page expects a site column.

[riasvdv]

Thanks a lot!