Speed up copy for ImageBuffer

[197g]

Benchmarks TBD but expecting ~60% performance or more. Motivation, context and approach from the first commit and follows pretty directly what was presented in the thoughts on #2553.

This has been a long standing issue. The lack of generalization in Rust
makes it generally hard to provide specialized implementations of
copy_from that can make full use of the layout information to improve
code generation. Since the argument is generic we stay with the default
implementation even for the very strict targets (and source) of
ImageBuffer.

We sidestep a large part of the problem by speeding up only the copy
from a well-described layout: View (a strided matrix). Then an
optional method on GenericImageView lets us query if the source is
equivalent to such a copy. We wont reap the benefits for user defined
trait impls but importantly the crate's own ImageBuffer and SubImage
can provide it The latter also has a generic impl for

SubImage<D> were <D as Deref>::Target: GenericImageView

Due to this we do not use a double-dispatch approach (adding a
copy_into_buffer) but this which composes purely at runtime.

Also note that DynamicImage can not provide it but the goal is to
replace this, too.

Closes: #2417, possibly #2553 (@fintelia addresses the immediate concern but we expanded the scope for reasons of extensibility concerns; but sealing the trait is already represented in another issue; your call)

[197g]

Rebased so we can run complete benchmarks. Although, it does not seem necessary to justify this any further.

Details

copy_from               time:   [2.9246 ms 2.9460 ms 2.9688 ms]
                        change: [-25.357% -24.766% -24.149%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 2 outliers among 100 measurements (2.00%)
  2 (2.00%) high mild

copy_at                 time:   [345.24 µs 346.54 µs 348.18 µs]
                        change: [-64.403% -63.765% -63.034%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 19 outliers among 100 measurements (19.00%)
  1 (1.00%) low mild
  9 (9.00%) high mild
  9 (9.00%) high severe

copy_view               time:   [552.29 µs 553.94 µs 556.02 µs]
                        change: [-78.457% -77.900% -77.345%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 14 outliers among 100 measurements (14.00%)
  1 (1.00%) low mild
  2 (2.00%) high mild
  11 (11.00%) high severe

copy_fill               time:   [704.57 µs 705.18 µs 705.79 µs]
                        change: [-78.583% -78.402% -78.128%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 6 outliers among 100 measurements (6.00%)
  2 (2.00%) high mild
  4 (4.00%) high severe

copy_strides            time:   [875.41 µs 876.36 µs 877.22 µs]
                        change: [-74.813% -74.428% -73.418%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 4 outliers among 100 measurements (4.00%)
  1 (1.00%) low mild
  2 (2.00%) high mild
  1 (1.00%) high severe