refactor: optimize dependency graph performances

[ndr-brt]

What this PR changes/adds

Does some little tweaks to DependencyGraph to improve performance, both time and memory wise.

The code used to measure the improvements has been put on ExtensionLoader in the loadServiceExtensions method:

Runtime runtime = Runtime.getRuntime();
var memoryUsed = runtime.totalMemory() - runtime.freeMemory();
System.out.println("USED MEMORY BEFORE: " + memoryUsed);
var l = System.currentTimeMillis();
System.out.println("CREATE DEPENDENCY GRAPH STARTED AT " + l);
var injectionContainers = new DependencyGraph(context).of(serviceExtensions);
System.out.println("DEPENDENCY GRAPH CREATED IN " + (System.currentTimeMillis() - l));
System.out.println("USED MEMORY BY DEP GRAPH: " + ((runtime.totalMemory() - runtime.freeMemory()) - memoryUsed));

With the changes put in place (details in the "further notes" section) I observed, measuring 10 times and extracting the mean value:

• execution time lowered by ≈ 20% (from 62,4ms to 48,1ms)
• memory used lowered by ≈ 5% (from 7.92Mb to 7.46Mb)

these improvements don't look really game changing, but they will be definitely helpful in multiple-connectors environment, plus it's always good to apply good code practices (see below)

Why it does that

startup performances

Further notes

The improvements evolve around:

• less loops on extensions: removed 2 unnecessary iterations
• avoid collection of streams if not really needed
• build injectionPoints sets to be put in injection containers directly when they are evaluated first, this is avoiding instantiation of N (number of extensions) streams and filter of the whole set of injection points.
• moved ReflectiveObjectFactory into junit module as it's only used in test context.

Linked Issue(s)

Closes # <-- insert Issue number if one exists

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