[SPDK] Copy framework rename

Hi Everyone,

For 20.04 we’re going to start expanding the capabilities of the existing copy framework. Actually, today it already does copy and memfill so the name “copy” isn’t really the best but when we add dif/dix and crc it will be even less accurate.

If you have input on the new naming, please provide it via reviewing the patch below.  It’s a bit more than just search/replace but only in a few of the files, most files it’s just replace ‘copy’ with ‘accel’ so don’t be afraid of the large number of files ☺

https://review.spdk.io/gerrit/c/spdk/spdk/+/576
global: rename copy to accel
The copy engine library, modules and public APIs have been renamed.
Use of the word `copy` has been replaced with the word `accel`
short for accelerator in preparation for adding new capabilities
in the future. Additionally, APIs for what was previously called
the `memcpy` engine have been renamed to identify the engine as a
software accelerator.

Thanks
Paul