[DO NOT MERGE] [pdata] Try append for slice.CopyTo

[dmitryax]

Trying consolidating the CopyTo logic for slices as suggested in #13267 (comment)

@bogdandrutu looks like the compiler is not that smart and we cannot use the append approach for the complex slices. See the results:

before

goos: darwin
goarch: arm64
pkg: go.opentelemetry.io/collector/pdata/internal
cpu: Apple M1 Max
BenchmarkCopyOrigSlice
BenchmarkCopyOrigSlice/0_to_7-10         	 6696460	       187.7 ns/op	     252 B/op	      10 allocs/op
BenchmarkCopyOrigSlice/1_to_7-10         	 6324669	       181.4 ns/op	     252 B/op	      10 allocs/op
BenchmarkCopyOrigSlice/7_to_7-10         	 6145800	       191.6 ns/op	     252 B/op	      10 allocs/op
BenchmarkCopyOrigSlice/10_to_7-10        	 4897490	       247.2 ns/op	     412 B/op	      11 allocs/op
BenchmarkCopyOrigSlice/20_to_7-10        	 3922288	       306.8 ns/op	     572 B/op	      11 allocs/op
BenchmarkCopyOrigSlice/50_to_7-10        	 2775319	       430.0 ns/op	    1148 B/op	      11 allocs/op
PASS

after

BenchmarkCopyOrigSlice/0_to_7-10         	 6255495	       188.3 ns/op	     252 B/op	      10 allocs/op
BenchmarkCopyOrigSlice/1_to_7-10         	 5359400	       186.6 ns/op	     252 B/op	      10 allocs/op
BenchmarkCopyOrigSlice/7_to_7-10         	 5916748	       206.2 ns/op	     252 B/op	      10 allocs/op
BenchmarkCopyOrigSlice/10_to_7-10        	 4371021	       264.9 ns/op	     476 B/op	      11 allocs/op
BenchmarkCopyOrigSlice/20_to_7-10        	 3081704	       395.6 ns/op	     924 B/op	      12 allocs/op
BenchmarkCopyOrigSlice/50_to_7-10        	 1881642	       631.2 ns/op	    1948 B/op	      13 allocs/op
PASS

10 allocations are spent to regenerate the destination slice

[codecov]

Codecov Report

Attention: Patch coverage is 29.16667% with 17 lines in your changes missing coverage. Please review.

Project coverage is 91.56%. Comparing base (c6cd1ae) to head (a035f59).

Files with missing lines	Patch %	Lines
pdata/internal/wrapper_value.go	22.72%	17 Missing ⚠️

❌ Your patch check has failed because the patch coverage (29.16%) is below the target coverage (95.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13293      +/-   ##
==========================================
- Coverage   91.61%   91.56%   -0.06%     
==========================================
  Files         522      522              
  Lines       29120    29139      +19     
==========================================
+ Hits        26679    26681       +2     
- Misses       1925     1942      +17     
  Partials      516      516              

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