deprecation of the existing libcal code in the theme

Now that displaying libcal events is largely done through the [libcal block](https://gitlab.com/cpl/cpl-libcal-block and that block should cover nearly all use cases (if it does not, please let me know, @MYoungCPL :))

I need to remove libcal specific code in our theme.

Most notably, the Informally from talking to @MYoungCPL ; the process for doing deprecating this would first begin by migrating each branch page into the default template instead of the location template (2023/24 Ernesto update: this was referring to an location template that was no longer used) (done by changing the page template that is being used for the location page and then inserting the libcal block into the page's content); would need to be done manually but should only take 3-5 minutes at most, per page. (THAT IS DONE)

As an example. https://cpl.org/locations/addison/ which has the migration done (using the CPL libcal block) and https://cpl.org/locations/mtpleasant/ which does not (uses the php template based style), (THAT IS DONE)

Why do this migration: Events are displayed consistently on our website; less code for us to fix and maintain.

• https://gitlab.com/cpl/ernesto/-/blob/main/content/content-music-at-main.php
• https://gitlab.com/cpl/tempera-nocopyrt/-/blob/main/content/content-location.php
• https://gitlab.com/cpl/tempera-nocopyrt/-/blob/main/content/content-libcalquery.php
• https://gitlab.com/cpl/tempera-nocopyrt/-/blob/cb497e7559663b420769ca619d58ed5159f51b60/functions.php#L56
• https://gitlab.com/cpl/tempera-nocopyrt/-/blob/main/js/libcal.js
• https://gitlab.com/cpl/tempera-nocopyrt/-/blob/main/js/libcal-location.js
• https://gitlab.com/cpl/ernesto/-/blob/main/js/libcal-music-at-main.js
• https://gitlab.com/cpl/ernesto/-/blame/86287452e5cef427d9e1cd5bc88e16f96991f906/stylesheets/layout/_grid.scss#L10
• https://gitlab.com/cpl/ernesto/-/blob/main/templates/template-music-at-main.php?ref_type=heads
• Will need to change all of those pages that used the location template
• delete the relevant ACF field groups that those pages relied on

Block-based templates could expedite migrating the location pages to use libcal block but I would give it at least several months before they would be ready to be used on our website (that's assuming that https://github.com/WordPress/gutenberg/issues/24803 is eventually resolved smoothly as well)