Add riscv64 linux tools download support

[bitsk]

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What kind of change does this PR introduce?

Hello, I recently successfully built the arduino-cli and Arduino IDE 2.0 on the RISC-V architecture SBC, Sipeed Lichee Pi 3A, based on the Linux distribution openKylin that it supports. After testing, this PR allows us to smoothly download packages for the riscv64-linux architecture. This is the first step for Arduino to support the RISC-V platform, and I will submit more PRs in the future to fully support the operation of Arduino in a RISC-V architecture desktop environment.

What is the current behavior?

Currently, the RISC-V architecture is not yet supported.

What is the new behavior?

The tools for the RISC-V architecture can be downloaded correctly.

Does this PR introduce a breaking change, and is titled accordingly?

Other information

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.67%. Comparing base (9e5deed) to head (add9b2e).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2700      +/-   ##
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+ Coverage   67.65%   67.67%   +0.02%     
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  Files         234      234              
  Lines       22205    22207       +2     
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+ Hits        15022    15028       +6     
+ Misses       6001     5998       -3     
+ Partials     1182     1181       -1     

Flag	Coverage Δ
unit	67.67% <100.00%> (+0.02%)	⬆️

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[cmaglie]

Thanks!

I've added the corresponding changes to the documentation.