Utility functions to transform enum to string and back.

[diptorupd]

Looks like a duplication. I see this code above. It is better to create function which transforms enum to string and back.

Originally posted by @PokhodenkoSA in #93 (comment)

Example code:

dpctl/backends/source/dppl_sycl_device_interface.cpp

Line 62 in bb41bb6

case info::device_type::cpu:

dpctl/backends/source/dppl_sycl_platform_interface.cpp

Line 129 in 9fcbaa5

case info::device_type::cpu:

Both examples contain conversion from enum to string. It is a code duplication and could be refactored into single function.
Also it is a good design to create pairs of functions to convert enum to string and string to enum.