What does this implement/fix? Explain your changes.

This PR refactors how AbstractConnectionResolver calculates the query amount in the following ways:

• Refactor ::get_query_amount() to only calculate the query amount 1x in the lifecycle, by checking if AbstractConnectionResolver::$query_amount is set.
• Source the default $max_query_amount from ::max_query_amount(), allowing child classes to overload the max amount without using the graphql_connection_max_query_amount filter. Child classes using that filter have been updated to set ::max_query_amount() instead.
• Move the graphql_connection_amount_requested filter into ::get_query_amount() to improve DX. The filter will only be applied once due to the aformentioned isset().
• Add a graphql_connection_default_query_amount filter, for changing the default query amount when no first or last argument is passed to the query.
• DRYout ::get_amount_requested().
• Replace direct calls to ::$query_amount with ::get_query_amount().
• Fixed logic in several ::get_query_args() child methods to rely on ::get_query_amount() and avoid unnecessary min()/max()ing.

There are no breaking changes in this release.

Does this close any currently open issues?

Part of #2749

Any relevant logs, error output, GraphiQL screenshots, etc?

Any other comments?

• The reason this is not a breaking change is that get_query_amount() is called both in ::get_args() and in the constructor, so there is no possibility of ::$query_amount being null in the child class. Since the types and method signatures, overloaded classes will work as they do currently, making the enhancements in this PR essentially opt-in (i.e. devs can refactor at their leisure).
• This PR is based on chore: prepare ConnectionResolver classes for v2 backport #3082 , which should be merged first.

Where has this been tested?

Operating System: Ubuntu 20.04 (wsl2 + devilbox + php 8.1.15)

WordPress Version: 6.4.3