Add option to ask which container a page should be open in when it has no site assigned to it

[bradsharp]

Introduces the select page which prompts the user to select the container they want to use when they open a site without a container already assigned to it. This encourages users to separate out their websites into containers if they wish, a common feature that I want myself and have also seen others ask for.

By default this setting is disabled but it can be enabled by the user if they go into the options menu.

An example of what the select page looks like with default containers:

I am not familiar with the localization process but I have edited the json files in the locales submodule. I would appreciate it if someone could explain to me what the intended way to include those is.

[KittyKatt]

Would this possibly fulfill the AC required to satisfy #2535 ? I've been keeping an eye on this issue for months and it feels like if I was asked to select a container for every tab that is not currently assigned to be auto-opened in a container, then the Ctrl-T new tab behavior would work as expected.

[unrealsolver]

Would it be possible to have manual rules, as it described here: #2134
The use case is mainly 3rd party apps that does not care about containers when opening a link.