Merge Montage & Montage Review page

[IgorA100]

I created a topic on the forum: https://forums.zoneminder.com/viewtopic.php?t=33288 about drastic changes to the Montage page. Now I have made the final decision to merge Montage & Montage Review page. Because a lot of code will overlap. On the Montage page there will be a switch in the form of two buttons, for example “Live” & “In recording” (the names of the buttons are not important and are being discussed). I plan to load all page data (including the monitor filter) via Ajax. There is a lot of work ahead, because... PHP uses a lot of global variables and few functions. I will transfer some of the code into functions. If I start using new classes and methods, then there will be a lot more work. To begin with, for example, I need “_monitor_filters.php” to not just display content on the page, but to return the generated content to a variable. Because I haven’t 100% studied how the code works, then I’ll probably come across my own erroneous path, which I’ll correct. I won't be able to change a lot of code at once and make 1-2 PRs. I suggest releasing PRs as some work is completed, otherwise I will definitely get confused by the changes. I don’t know how clearly I expressed my thoughts, because... There is a language barrier.