homepages/homepage.php: Remove the glob; make the list of files to be included explicit

[benlk]

https://github.com/INN/largo/blob/3e9ad47b4e19c328be6699d81ee8720b5f460594/homepages/homepage.php#L8-L10

• [ ] Replace the glob with an explicit list of files to be included. Why?
  • We know what files we want to include, so there's no need to perform a search through the filesystem to find the files to be included. This should result in slight memory usage decreases and load speed increases, as well as time spent waiting for filesystem access.
  • We want to push sites toward making child themes where they handle their own includes. Related: #1512
• [ ] Validate the paths and require_once in accordance with https://github.com/INN/largo/issues/1494
• [ ] Make a note of the end-of-glob in the changelog; it's a breaking change so we should make a note along the lines of:

  Removes the use of glob() for making a list of homepage layouts to be include()ed from homepages/layouts/ — this only affects you if you aren't using a child theme but have instead placed your homepage layout directly in Largo.

[benlk]

The 0.5-dev branch that was the target of https://github.com/INN/largo/pull/1628 was deleted, but those changes can be applied to 0.7 and the author @seanchayes referenced in the reimplementation PR.

[benlk]

remove glob in homepage file list