Ensure that important RAM modes are exposed to Yosys

[litghost]

Currently only a handful of RAM configurations are available to Yosys. For example, RAM64X1S is not exposed, nor is any of the RAM32X1[DS] nor RAM32M or RAM64M.

It is unclear which of these are high value, but in at least the case of murax, Vivado choose to use some RAM32X1S, which pack tighter than either RAM32X1D or RAM64X1D.

Existing PRs that need to be tested and landed:

• add RAM32X1D inference #33
• enable inference for RAMB36E1 #31