Add portenta C33 firmware to the plugin system

[umbynos]

No description provided.

[alessio-perugini]

LGTM.
Self-future reminder: don't merge this before releasing the plugin and publish it to the general package_index.json

[codecov-commenter]

Codecov Report

Patch coverage: 11.76% and project coverage change: +5.08% 🎉

Comparison is base (bb28293) 6.63% compared to head (f1747cf) 11.72%.
Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##            main     #206      +/-   ##
=========================================
+ Coverage   6.63%   11.72%   +5.08%     
=========================================
  Files         24       20       -4     
  Lines       2154     1160     -994     
=========================================
- Hits         143      136       -7     
+ Misses      1953      971     -982     
+ Partials      58       53       -5     

Flag	Coverage Δ
unit	11.72% <11.76%> (+5.08%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
cli/arguments/arguments.go	0.00% <0.00%> (ø)
cli/certificates/flash.go	0.00% <0.00%> (ø)
cli/common/common.go	0.00% <0.00%> (ø)
cli/firmware/flash.go	0.00% <0.00%> (ø)
cli/firmware/getversion.go	0.00% <0.00%> (ø)
cli/firmware/list.go	0.00% <0.00%> (ø)
flasher/flasher.go	0.00% <ø> (ø)
indexes/download/download.go	29.75% <100.00%> (-2.63%)	⬇️
indexes/firmwareindex/firmwareindex.go	55.07% <100.00%> (+6.35%)	⬆️

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