Handle inheritance of <debug> element attributes

[jnkr-ifx]

The spec states: https://open-cmsis-pack.github.io/Open-CMSIS-Pack-Spec/main/html/pdsc_family_pg.html#element_debug

Multiple debug elements can be defined which are either specific to a
processor identified by attribute Pname, or which apply to all
connections.

The current implementation did not handle this correctly: it only looked for a single debug element defined on either the device or subfamily. Debug attributes can be defined on the family as well; and if the innermost debug element does not have the attribute we're looking for, we need to look at debug elements on parent elements rather than assuming it's undefined.

This patch is necessary to correctly parse PSOC 6 CMSIS packs, which define debug elements at the family level and define additional attributes at more specific levels:

<family Dfamily="PSoC 62" Dvendor="Infineon:7">
  <processor Pname="Cortex-M0p" Dcore="Cortex-M0+" DcoreVersion="r0p1" Dfpu="NO_FPU" Dmpu="MPU" Dendian="Little-endian" Dclock="100000000" />
  <processor Pname="Cortex-M4" Dcore="Cortex-M4" DcoreVersion="r0p1" Dfpu="SP_FPU" Dmpu="MPU" Dendian="Little-endian" Dclock="150000000" />
  <debug Pname="Cortex-M0p" __ap="1" defaultResetSequence="ResetProcessor" />
  <debug Pname="Cortex-M4" __ap="2" defaultResetSequence="ResetSystem">
  ....
  <subFamily DsubFamily="CY8C62x4">
    <debug Pname="Cortex-M0p" svd="SVD/psoc6_04.svd" />
    <debug Pname="Cortex-M4" svd="SVD/psoc6_04.svd" />

[mathias-arm]

It seems we are going to have to fix CI.

[mathias-arm]

Can you rebase for CI to run?

[mathias-arm]

My only concern is that the changes to the Debug struct makes it an API change.

@jnkr-ifx: What software are you using this change with?

[jnkr-ifx]

@mathias-arm I don't think this is a public API change -- the device module is private and the Debug struct is not reexported:

cmsis-pack-manager/rust/cmsis-pack/src/pdsc/mod.rs

Lines 14 to 17 in f1cadeb

	mod device;
	pub use component::{ComponentBuilders, FileRef};
	pub use condition::{Condition, Conditions};
	pub use device::{AccessPort, Algorithm, Core, Device, Devices, Memories, Processor};

I'm using this with probe-rs's target-gen tool, and Infineon CAT1A and CAT1B CMSIS packs

[ithinuel]

little nit, otherwise looks fine by me.