Override the default kint dumper

Problem/Motivation

By introducing a second kint dumper instead of overriding the default one, we introduce a lot of issues/unwanted behaviour:

• #3224258: Add a way to call this module if it is not the default dumper (introducing a new Twig function would no longer be necessary)
• #3193458: Extras are not showing when using the kint Twig function (the kint Twig function is hardcoded to use the twig dumper plugin, so it doesn't work with our extended version without overriding/duplicating code
• We can't override the procedural kint function without messing with the order of modules in code.extension, which feels messy and brittle.

The only feature we lose is having the possibility to invoke kint without showing extras, but I don't believe that use case outweighs the benefits. Please correct me if I'm wrong.

Proposed resolution

Override the default kint dumper instead of providing a separate one.

Remaining tasks

• Override the default kint dumper
• Provide an upgrade path from previous versions of the module
• Update the docs, since configuration will no longer be necessary