Create archive templates for block and oik-plugins custom post types

[bobbingwide]

The general purpose archive.html template embeds the a2z-pagination.html template part

<!-- wp:template-part {"slug":"a2z-pagination","theme":"fizzie"} /-->

which contains

<!-- wp:paragraph -->
<p>[bw_terms]</p>
<!-- /wp:paragraph -->

By default the [bw_terms] shortcode uses the letters taxonomy.
For Plugins and Themes this is OK.
But for Blocks we need to use the block letters taxonomy.

Thererfore we need separate template files archive-block.html and archive-block_example.html both of which will reference a block-a2z-pagination.html template part that contains the shortcode [bw_terms block_letters].

Also, the post_type attribute needs to be specified.
Therefore we also need archive-oik-plugins.

[bobbingwide]

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