feat: allows get to resolve services as singletons

[aidan-casey]

Based on the conversations with @Crell in the Tempest discord, this PR allows services to be shared by default and adds a secondary make method that always retrieves a new instance of the class.

Note the definition of the make method that PHP-DI has:

The make() method works like get() except it will resolve the entry every time it is called. Depending on the type of the entry this means:

• if the entry is an object, an new instance will be created every time
• if the entry is a factory, the factory will be called every time
• if the entry is an alias, the alias will be resolved every time

Please note that only the entry you ask for will be resolved every time: all the dependencies of the entry will not! That means that if the entry is an alias, the entry the alias points to will be resolved only once.

https://php-di.org/doc/container.html#make

[github-actions]

Benchmark Results

Comparison of add-singleton-by-default against 3.x (7e5cff65349956e14578e826a95d1f3ce6953761).

Open to see the benchmark results

Benchmark	Set	Mem. Peak	Time	Variability
ViewRenderBench(benchPlainHtml)	-	22.028mb +0.01%	492.388μs -7.75%	±1.34% -56.95%

_{Generated by phpbench against commit a6a9cfe}

[innocenzi]

Not a blocker, but I am not a fan of this:

• get gets a hidden behavior
• make does what get used to do
• get and make aren't clear names, they have minor differences in their behavior, so consumers have to read docs or code dive

I feel like we're unlocking a niche use case while making the container more confusing. I don't have an alternative to suggest, however.

[xHeaven]

I've reviewed this PR internally on Discord, but here is the review for clarity:

A couple things:

1. PR says make() always returns a new instance. This is true... unless you called get() earlier.

$container = new GenericContainer(
    getClassAsSingletonByDefault: true,
);

$get = $container->get(Mailer::class);
make = $container->make(Mailer::class);

var_dump($get === $make); // true

2. PR says make() always returns a new instance. This could be true... but now you just get a (false) CircularDependencyEncountered exception if you call make() more than once on the same class because the first call leaves the class constructor in the chain, and that's what the second call sees, so it's not a true circular dependency.
3. Though I'm not sure if this was in the scope, but with the current method, constructor dependencies are still not shared. So $mailer->platform === $platform is a false, even if they are the "same-ish" objects