Create DARWINF4SX1280 target

[DMAXYANG]

Create DARWINF4SX1280 target Based on RC7, Attached is the test firmware
betaflight_4.3.0_DARWINF4SX1280.zip

[blckmn]

AUTOMERGE: (FAIL)

• github identifies PR as mergeable -> FAIL
• assigned to a milestone -> FAIL
• cooling off period lapsed -> PASS
• commit count less or equal to three -> PASS
• Don't merge label NOT found -> PASS
• at least one RN: label found -> FAIL
• Tested label found -> FAIL
• assigned to an approver -> FAIL
• approver count at least three -> FAIL

[haslinghuis]

We do not want to add any more non-unified targets. Use an unified target instead.

Reference; #11565

[SteveCEvans]

@haslinghuis This is an SX1280 target and thus isn't supported by the STM32F411 target. Perhaps we should be adding an STM32F411SX1280 unified target?

[haslinghuis]

Okay, it was denied for EMAX. A STM32F411SX1280 unified target sounds good, Then we can also convert BetaFPV, CrazyBee and maybe other targets as didn't check.

[haslinghuis]

@SteveCEvans there is no time anymore for a new target, Can you prepare please?
In the mean time should we accept this for 4.3

[SteveCEvans]

I'm preparing a PR for an STM32F411SX1280 unified target.

[DMAXYANG]

@SteveCEvans Thank you, I will PR a unified target when you are done.

[SteveCEvans]

Please see #11648 and betaflight/unified-targets#623