log: Add ValueFromAttribute and KeyValueFromAttribute

[pellared]

Fixes #6158

Related spec PR: open-telemetry/opentelemetry-specification#4373

Benchmark results:

goos: linux
goarch: amd64
pkg: go.opentelemetry.io/otel/log
cpu: 13th Gen Intel(R) Core(TM) i7-13800H
BenchmarkKeyValueFromAttribute/Empty-20              72029505                16.47 ns/op            0 B/op          0 allocs/op
BenchmarkKeyValueFromAttribute/Bool-20               68560222                16.99 ns/op            0 B/op          0 allocs/op
BenchmarkKeyValueFromAttribute/BoolSlice-20          14647401                76.21 ns/op           50 B/op          2 allocs/op
BenchmarkKeyValueFromAttribute/Int64-20              70737378                16.92 ns/op            0 B/op          0 allocs/op
BenchmarkKeyValueFromAttribute/Int64Slice-20         16780069                96.87 ns/op           64 B/op          2 allocs/op
BenchmarkKeyValueFromAttribute/Float64-20            59299638                16.93 ns/op            0 B/op          0 allocs/op
BenchmarkKeyValueFromAttribute/Float64Slice-20       12691222               106.2 ns/op            64 B/op          2 allocs/op
BenchmarkKeyValueFromAttribute/String-20             63837711                16.97 ns/op            0 B/op          0 allocs/op
BenchmarkKeyValueFromAttribute/StringSlice-20         9251001               114.7 ns/op            80 B/op          2 allocs/op
PASS
ok      go.opentelemetry.io/otel/log    14.776s

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.2%. Comparing base (538e869) to head (cf3329c).
Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #6180   +/-   ##
=====================================
  Coverage   82.2%   82.2%           
=====================================
  Files        273     273           
  Lines      23674   23720   +46     
=====================================
+ Hits       19478   19521   +43     
- Misses      3849    3852    +3     
  Partials     347     347           

see 2 files with indirect coverage changes