Support `has_archive` parameter set to a string value such as `shop`

[bobbingwide]

oik-types allows the definition of a post type to be overridden. When overriding the product post type the string value of shop for the has_archive parameter was lost. This led to an incorrect setting of the archive prefix for products. The result was that the Shop page was not displaying the default shop display.

See https://github.com/bobbingwide/wizzie/issues/10#issuecomment-1177324628

Requirement

• Allow user to set the has_archive parameter to a string value such as shop.

Proposed solution

• The code should cater for existing definitions where the has_archive value is 0 for false and either 1 or on for true
• The string value should only be used when the checkbox is set.

[bobbingwide]

Delivered in v2.3.0 on oik-plugins.