Add new register-related libraries to the repo.

caliptra-registers-generator (fw-caliptra/registers/bin/generator)

  A binary that takes the .rdl files as input, parses them with
  caliptra-systemrdl, uses caliptra-ureg-systemrdl to generate a ureg
  schema, tweaks the schema a bit (renames, etc), then passes the schema
  to caliptra_ureg_codegen to generate the register-access rust code.

caliptra-registers (fw-caliptra/registers)

  The full set of types for accessing caliptra
  registers (generated by caliptra-ureg-codegen)

caliptra-systemrdl (fw-caliptra/systemrdl)

  A general purpose systemrdl parser library written in rust.

ureg (fw-caliptra/ureg)

  General-purpose register traits and glue code; used by caliptra-registers.

ureg-schema (fw-caliptra/ureg/lib/schema)

  Types for defining a schema of register blocks

ureg-codegen (fw-caliptra/ureg/lib/codegen)

  Library for generating rust register types from ureg schema

ureg-systemrdl (fw-caliptra/ureg/systemrdl)

  Library for generating ureg schema from a set
  of .rdl files (uses caliptra-systemrdl)