Record links/events attribute drops independently

[MrAlias]

Added

• The Event and Link struct types from the go.opentelemetry.io/otel package now include a DroppedAttributeCount field to record the number of attributes that were not recorded due to configured limits being reached.
• The Jaeger exporter now reports dropped attributes for a Span event in the exported log.

Changed

• The DroppedAttributeCount field of the Span in the go.opentelemetry.io/otel package now only represents the number of attributes dropped for the span itself. It no longer is a conglomerate of itself, events, and link attributes that have been dropped.

Resolves #1766

[codecov]

Codecov Report

Merging #1771 (5f366c1) into main (5bbfc22) will decrease coverage by 0.0%.
The diff coverage is 100.0%.

@@           Coverage Diff           @@
##            main   #1771     +/-   ##
=======================================
- Coverage   78.7%   78.7%   -0.1%     
=======================================
  Files        134     134             
  Lines       7140    7144      +4     
=======================================
  Hits        5626    5626             
- Misses      1270    1272      +2     
- Partials     244     246      +2     

Impacted Files	Coverage Δ
trace/trace.go	86.7% <ø> (ø)
exporters/trace/jaeger/jaeger.go	93.8% <100.0%> (+0.1%)	⬆️
sdk/trace/span.go	94.0% <100.0%> (ø)
sdk/metric/refcount_mapped.go	77.7% <0.0%> (-22.3%)	⬇️
sdk/metric/sdk.go	80.2% <0.0%> (-1.2%)	⬇️

[paivagustavo]

LGTM

nit: We should be able to remove the assignment sd.DroppedAttributeCount = int(s.droppedAttributeCount), on the span.Snapshot() method, since the span.droppedAttributeCount is only populated by the attributesMap now.