[csolution] Extend processor attributes

[brondani]

With the advent of CMSIS-DFP where each device is described only with a single superset entry containing all features enabled, for using subset variants the expectation is to leave it to project settings to disable/change features.

For allowing the device features selection I am proposing to extend the processor attributes with the following items:

• fpu: dp, sp, off - DfpuEnum
• dsp: on, off - DdspEnum
• mve: fp, int, off - DmveEnum
• endian: little, big (implemented but undocumented) - DendianEnum
• branch-protection: bti, bit-signret, off (covered by [csolution] Add branch protection toolchain agnostic enablement  #1069)

[edriouk]

I would suggest using not only CMSIS enums, but also attributes from pdsc:

Dfpu: NO_FPU, SP_FPU, DP_FPU - DfpuEnum
Ddsp: DSP, NO_DSP - DdspEnum
Dmve: NO_MVE, MVE, FP_MVE - DmveEnum
Dndian: Little-endian, Little-endian - DendianEnum

This has the following advantages:

• consistent with pack description
• consistent with RTE Model usage
• no need to convert name and values => can directly be passed to condition evaluation
• future attributes can be also supported without need to change a tool

[brondani]

Implemented in #1191
@ReinhardKeil can you please update the documentation?
The schema descriptions can be found here:
https://github.com/Open-CMSIS-Pack/devtools/pull/1191/files#diff-2fed5eb3550b2bc74902a4863e1a4efc35f995e27d2b4ddecf1c1620e1b3fd29

[ReinhardKeil]

Documented here https://github.com/Open-CMSIS-Pack/cmsis-toolbox/blob/main/docs/YML-Input-Format.md#processor

I think this can then be closed. endian is not documented as I don't know any use case.