Better user interface to edit reverse DNS servers (`dns.revServers`)

[rdwebdesign]

trafficstars

What does this PR aim to accomplish?

Replace the current single <textarea> with a table. Each reverse server will be in a separate row and each field will be in a separate table cell.

A small legend will improve usability (maybe we will need to change the help text).

NOTE:

~~Depends on https://github.com/pi-hole/web/pull/2885~~ (already merged)

How does this PR accomplish the above?

Using datatables plugin and a few functions to deal with dns.revServers entries.

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[rdwebdesign]

The first thing I noticed was my currently defined revServer cannot be disabled.

This is expected... In the current state, this PR can only add and delete entries. I didn't create functions to edit fields (this checkbox is just a nice way to display true/false values).

I hope the reason is: because you are adding editing

This is in my todo list.

[github-actions[bot]]

This pull request has conflicts, please resolve those before we can evaluate the pull request.

[github-actions[bot]]

Conflicts have been resolved.

[github-actions[bot]]

This pull request has conflicts, please resolve those before we can evaluate the pull request.

[github-actions[bot]]

Conflicts have been resolved.