Metrics aggregate map is generic over temporality

[fraillt]

Changes

Same functionality as in #2506, but in my opinion a bit simpler and even cleaner.
The thing that I especially like, is how elegant is concrete implementation for an aggregation.

pub(crate) struct SumNew {
    pub(crate) monotonic: bool,
}

impl<T> AggregationImpl<T> for SumNew
where
    T: Number,
{
    type Aggr = Increment<T>;
    type AggrData = data::Sum<T>;

    fn precompute(&self, value: T) -> T {
        value
    }

    fn new_aggregation_data(&self, temporality: Temporality, time: AggregateTime) -> data::Sum<T> {
        data::Sum {
            data_points: vec![],
            start_time: time.start,
            time: time.current,
            temporality,
            is_monotonic: self.monotonic,
        }
    }

    fn reset_aggregation_data(
        &self,
        existing: &mut data::Sum<T>,
        temporality: Temporality,
        time: AggregateTime,
    ) {
        existing.data_points.clear();
        existing.start_time = time.start;
        existing.time = time.current;
        existing.temporality = temporality;
        existing.is_monotonic = self.monotonic;
    }

    fn build_create_points_fn(
        &self,
    ) -> impl FnMut(Vec<KeyValue>, &Increment<T>) -> SumDataPoint<T> {
        |attributes, aggr| SumDataPoint {
            attributes,
            value: aggr.value.get_value(),
            exemplars: vec![],
        }
    }
}

Yep, that's full implementation for Sum :) all the other common stuff is in aggregate_impl.rs file.
I deliberately didn't remove existing code, so it would be easier to evaluate this new design, and once we're happy with it, we can apply it.

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

Attention: Patch coverage is 97.05882% with 4 lines in your changes missing coverage. Please review.

Project coverage is 77.5%. Comparing base (90b0dd4) to head (bdc6ecd).

Files with missing lines	Patch %	Lines
opentelemetry-sdk/src/metrics/data/mod.rs	50.0%	3 Missing ⚠️
...pentelemetry-sdk/src/metrics/internal/aggregate.rs	92.8%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #2530     +/-   ##
=======================================
- Coverage   77.8%   77.5%   -0.3%     
=======================================
  Files        123     124      +1     
  Lines      23059   23194    +135     
=======================================
+ Hits       17940   17981     +41     
- Misses      5119    5213     +94     

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