Add server runtime metrics aggregator

[AbhiPrasad]

This task can only be done once #9794 is merged in.

Add a MetricsAggregator implementation for ServerRuntimeClient, meant to be used in Node, Deno, Bun, Vercel Edge, etc.

https://github.com/getsentry/sentry-javascript/blob/develop/packages/core/src/server-runtime-client.ts

Instead of requiring the Metrics integration, this should instead gate functionality under an _experiments flag passed into client options. See

sentry-javascript/packages/types/src/options.ts

Lines 200 to 205 in 93bbeb7

	/**
	* Options which are in beta, or otherwise not guaranteed to be stable.
	*/
	_experiments?: {
	[key: string]: any;
	};

This needs to build off the SimpleMetricsAggregator, but needs to fully defined the aggregator behaviour defined in https://develop.sentry.dev/sdk/metrics/#aggregator-behavior

1. 10 Second Bucketing: The SimpleMetricsAggregator has no timestamp based bucketing system - this needs to be introduced.
2. Flush Shift: The SimpleMetricsAggregator flushes every 5 seconds, but introduces no jitter pattern. The server runtime metrics aggregator needs to add jitter to reduce load concerns when a set of SDKs on a fleet of machines are all initialized at once (need to randomly offset flush intervals).
3. Force flush: The SimpleMetricsAggregator does not have any weight-based force flush mechanisms, this needs to be added
4. Background Aggregation: This doesn't have to be done for the v0, we can come back and add it on later on

Please use https://github.com/getsentry/sentry-python/blob/master/sentry_sdk/metrics.py as a reference implementation.

As a next step, we'll need to add support for:

1. metric summaries: https://github.com/getsentry/rfcs/blob/main/text/0123-metrics-correlation.md
2. code locations: https://develop.sentry.dev/sdk/metrics/#meta-data

[AbhiPrasad]

This is now implemented! #9973

Will open new issues for code locations and metric summaries