git-subtree-dir: raltool
git-subtree-split: 73b33d9

Child commits apply the patches that turn it into raltool. This merge
tracks to a commit on the chiptool master branch.

Merge commit '0ceb38148dd666895640afd1fc4e6ae265f7676c' as 'raltool'

Using stable.

The BitSize newtype helped with refactoring, and could be removed if
deemed too noisy. After this commit, the size of a set of fields is
based on the size of the register.

Before this commit, the registers for an MIMXRT PWM peripheral were all
incorrectly u32s. After this commit, I observed that code generated for
an MIMXRT PWM peripheral used u16 throughout. It still might use u8 for
individual fields, but that doesn't affect the MMIO register
interactions. Only tested by extracting peripherals, then generating
blocks based on the YAML output; haven't tested a full SVD -> PAC
transform, but I would expect that to work.

Combine lets us consolidate enums, fieldsets, and blocks across devices.
Given multiple IRs, combine figures out the various versions of these IR
elements, then creates a new IR that shares as much as it can. The
heuristics for combining these IR elements is encoded in the combine
module.

When a block is used across multiple peripheral instances, remove any
number suffix.

Remove the strong types, favoring a RAL-like pattern for accessing
register fields and enums. This is achieved by nesting the render calls
during codegen.

I plan to subtree this project directly into imxrt-ral. That project's
CI will cover this build.

If you discard type information, it's nice to have a way to re-acquire
the N associated with a peripheral. This commit introduces the `number`
functions for that purpose. This can let users create thin drivers just
around a register block static reference, and only acquire the
number at runtime.

Document this new function as an advanced usage, along with one other
(unrelated) usage pattern.

Hide the `steal()` method; it's only available for RTIC. Users should
call their own `instance()` methods.