Blog list layout: no need for row/col-12 grid styling of content

[chalin]

• Contributes to Upgrade to Bootstrap 5.2 #470
• Closes [BSv5] Blog posts page has layout issues #1571
• Drops the unnecessary use of row/col-12 combos. The main content doesn't need any grid styling.

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It is a bit hard to see, but there are no content changes in the layout other than:

• Replacing <div class="row"><div class="col-12">{{ if .Pages -}}...</div></div> by
  <div class="td-blog-posts">{{ if .Pages -}}...</div>
• And similarly replacing the divs for the pagination
• Change from <h2> to <div class="h2"> of the post-list header

Note that the class names td-blog-posts* currently have not styles associated with them.

In the before and after images, note the following fixes:

• The RSS button is flush-right and no longer takes up a column's worth of space
• Spacing above the View page source page-meta buttons

Before

After

Showing the pagination buttons:

[deining]

As seen in the preview, the spacing above the View page source buttons is not fixed by this PR. I tried locally too, both with chrome and firefox and I'm always getting the same, deficient result.

[chalin]

Thanks for noticing that. I had only looked at the build of the example site -- it is strange that the page-meta spacing would be fixed there. I've stuck out that item from the opening comment -- it wasn't the original issue targeted by this PR. I can track the page-meta issue separately:

• Page-meta spacing is off for some pages #1573

Any other comments @deining?

[deining]

With the spacing issue moved out of #1573, this PR looks good to me now.