Memory Bank Information proposal

[multiplemonomials]

Finally finished a new proposal I've been working on, for one of the first big new features that we are adding to Mbed. It's something that's been sorely needed for some time: a way for the build system to provide information about the memory banks on a device. This used to exist in Mbed CLI 1 but was never ported over to CMake and Mbed CLI 2. I say it's high time we get this information back, and in a more configurable and detailed way!

Please check out the proposal if you have a chance and submit any feedback here! I'm interested to hear what people have to say about this; let me know if there are any features you want or use cases I missed!