Add Performance tests for memory usage

[philipphofmann]

We can use the following code to measure the utilization of memory in tests.

measure(metrics: [XCTMemoryMetric()]) {
    
    startMeasuring()
    
    // Your Code
}

It makes sense to add these for:

• SDKInit
• Capturing events

[philipphofmann]

The problem with this is that we can't correctly run these tests in CI. See #1482.