Unify the platform libraries and add platform initialization routine

[cfernald]

• Merge the platform specific libraries into a single library
• Introduce PlatformIpmiInitialize to allow platform specific initialization logic
• Clean up the generic IPMI PEIM & SMM module
• Remove the unused context pointer from within generic IPMI

[apop5]

There is still the possibility that both Dxe and Smm can run the initialization code, when Pei gIpmiBmcHobGuid is not available.

Given that this is a possibility, in platforms that do not have a traditional Pei phase, should we consider something to address that in the future?

[cfernald]

There is still the possibility that both Dxe and Smm can run the initialization code, when Pei gIpmiBmcHobGuid is not available.

Given that this is a possibility, in platforms that do not have a traditional Pei phase, should we consider something to address that in the future?

This is something I considered, but didn't have a clear idea on how to solve this potential issue. I created issue #17 for this to keep track of this though.