Move Hypercall interface in distinct crate

[jounathaen]

This should enhance readability and allows reusing code in libhermit. Currently, the hypercall interface there is just copy-pasted.

Open points:

• Throw out the constants.
• Remove unused NETREAD|NETSTAT|NETWRITE hypercalls.
• Introduce a version checking mechanism.
• Use a common cargo workspace with uhyve
• Ensure stable compilation
• Think about a way to make this compatible with non-portIO architectures (aka: not x86 architectures) (related: add AARCH64 support on Linux #324 add AARCH64 support on macOS  #325 )
• Generalize this from Hypercall Interface to Uhyve-Interface and accommodate things like UART_PORT as well.
• Enhance the naming of the parameters.

[codecov]

Codecov Report

Merging #452 (dc7da20) into master (a696cb1) will decrease coverage by 0.57%.
The diff coverage is 46.40%.

@@            Coverage Diff             @@
##           master     #452      +/-   ##
==========================================
- Coverage   64.04%   63.47%   -0.57%     
==========================================
  Files          16       18       +2     
  Lines        2197     2204       +7     
==========================================
- Hits         1407     1399       -8     
- Misses        790      805      +15     

Impacted Files	Coverage Δ
uhyve-interface/src/parameters.rs	0.00% <0.00%> (ø)
uhyve-interface/src/lib.rs	5.55% <5.55%> (ø)
src/linux/vcpu.rs	71.73% <44.00%> (+1.35%)	⬆️
src/vm.rs	76.08% <72.91%> (-0.77%)	⬇️

[mkroening]

Great initiative. 👍

Are clippy and doc CI run automatically for this workspace member?

Could you squash a few commits together?

[jounathaen]

Thank you for your nice and extensive review! I'll implement the changes, hopefully next week. :-)