Drop MSP_ANALOG frame support

[DzikuVx]

All clients are required to switch to MSP2_INAV_ANALOG frame instead that provides all relevant data

[stronnag]

Appreciate your point about "All clients are required to switch to MSP2_INAV_ANALOG"; but this is exactly how we lost third party tools like 'Ezgui' and 'Mobile Flight'.

If the 3rd party client wants to support other MSP based FCs / older INAV, rather than testing for different versions of "ANALOG", history suggests that they may just not bother.

[sensei-hacker]

I'm curious how many third-party applications exist at this point. I know two third parties, and one of those is rather close to being first party.

If there are only one or two of any consequence, perhaps we could consider those two specifically?

[DzikuVx]

The list of clients is rather short indeed. EzGui was lost for multiple reasons, changing API was one of them.
I do wonder how long we should keep support for frames that have better alternatives

[b14ckyy]

SB app and MWP are the most important still maintained ones and FlyMe2TheMoon LUA is the third one currently implementing INAV support. I assume he will go for up2date stuff anyway. And don't forget impload.

[sensei-hacker]

These commands are being marked as deprecated in #11315 first, to give third-party developers notice before removal.

[sensei-hacker]

Conflict resolution + docs gap completed:

• Merged maintenance-10.x into this branch (merge commit) to resolve the 2024-era staleness; conflicts resolved locally, preserving this PR's single-command drop and any newer commands that were adjacent in fc_msp.c/msp_protocol.h.
• Completed the missing docs: removed the dropped command's entry from docs/development/msp/msp_messages.json (version bumped 2.1.0 → 3.0.0, breaking schema change), removed the corresponding README.md section/TOC, and cleaned cross-references.
• Verified the drop is complete in the firmware handler (fc_msp.c), protocol header (msp_protocol.h), and docs.

CI is running; mergeable against maintenance-10.x.

[github-actions]

Test firmware build ready — commit a379aea

Download firmware for PR #9920

247 targets built. Find your board's .hex file by name on that page (e.g. MATEKF405SE.hex). Files are individually downloadable — no GitHub login required.

Development build for testing only. Use Full Chip Erase when flashing.

[github-actions]

RAM / Flash usage vs. base branch — commit a379aea

No size baseline is available yet for this PR's base commit (no per-commit baseline has been published for it). This comment will show deltas once one exists — rebasing the PR refreshes its base commit.

Target	Flash Δ	RAM Δ
MATEKF405	700855 B (no baseline)	149532 B (no baseline)
MATEKF722	465475 B (no baseline)	125276 B (no baseline)
MATEKF765	733063 B (no baseline)	165468 B (no baseline)
MATEKH743	771159 B (no baseline)	167904 B (no baseline)

See RAM/flash optimization guide for techniques to reduce usage.