Update Spi component to return a status on device access

[djbyrne17]

Related Issue(s)	#4140
Has Unit Tests (y/n)	n
Documentation Included (y/n)	n
Generative AI was used in this contribution (y/n)	n

---

Change Description

1. Add enum SpiStatus to include values for each error already noted in Events.fppi
2. Convert Spi access port from "sync" to "guarded", consistent with I2C port. (In Drv/Interfaces/Spi.fpp)

Rationale

This would bring it in line with other similar drivers like I2C.

Testing/Review Recommendations

Unit Test is currently broken. Should be fixed to do one or several of:

• At least not run all the other UTs, as reported in Issue #4405
• Run on any supported platform, possibly just a subset of tests.
• Run only on a linux development workstation.
• Require specific hardware to run.

Future Work

Issue #4470 captures more work to go on this component, including

1. Fix / create Unit Test
2. Add docs/sdd.md
3. Add SpiStatus to other existing function

AI Usage (see policy)

N/A

[thomas-bc]

Looks good! Let's address the TODOs and we should be good to go

[thomas-bc]

Ah also you will need to format your files. This can be done with this one-liner:

git diff --name-only devel...HEAD | fprime-util format --stdin

[thomas-bc]

Looks good to me, but I'd like a second set of eyes to run through the comment below.

cc @LeStarch

[thomas-bc]

I believe this should be ok; but also Googling around seems to suggest there might be use cases for unidirectional SPI, so I wonder if we really should assert here? I'd like to get someone else's eyes on this to confirm, since we weren't asserting before.