Added the internal/observ package to log

[yumosx]

• part of Logs SDK observability - simple processor metrics #7016

goos: darwin
goarch: arm64
pkg: go.opentelemetry.io/otel/sdk/log/internal/observ
cpu: Apple M3
                            │ bench_res.txt │
                            │    sec/op     │
SLP/LogProcessed-8             0.8900n ± 2%
SLP/LogProcessedWithError-8     119.2n ± 5%
geomean                         10.30n

                            │ bench_res.txt │
                            │     B/op      │
SLP/LogProcessed-8             0.000 ± 0%
SLP/LogProcessedWithError-8    232.0 ± 0%
geomean                                   ¹
¹ summaries must be >0 to compute geomean

                            │ bench_res.txt │
                            │   allocs/op   │
SLP/LogProcessed-8             0.000 ± 0%
SLP/LogProcessedWithError-8    3.000 ± 0%
geomean                                   ¹
¹ summaries must be >0 to compute geomean

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.1%. Comparing base (f1ba319) to head (45d801a).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #7532   +/-   ##
=====================================
  Coverage   86.1%   86.1%           
=====================================
  Files        295     296    +1     
  Lines      21550   21594   +44     
=====================================
+ Hits       18557   18599   +42     
- Misses      2620    2622    +2     
  Partials     373     373           

Files with missing lines	Coverage Δ
sdk/log/internal/observ/simple_log_processor.go	100.0% <100.0%> (ø)

... and 1 file with indirect coverage changes

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[MrAlias]

Looks good overall. One minor documentation change needed.