Display average RPM on motor tab

[atomgomba]

Display average motor RPM above Master slider if the following conditions are met:

• DSHOT telemetry is enabled
• There is no telemetry error
• All motors are given the same output (i. e. the Master slider is used to change motor output)

I'm using average RPM when setting up dynamic idle RPM, but so far I had to calculate it manually and so I thought it would be useful to let the Configurator do the calculation instead.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
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No Coverage information
0.3% Duplication

[github-actions]

Do you want to test this code? Here you have an automated build:
Betaflight-Configurator-Android
Betaflight-Configurator-Linux
Betaflight-Configurator-macOS
Betaflight-Configurator-Windows
WARNING: It may be unstable and result in corrupted configurations or data loss. Use only for testing!

[blckmn]

AUTOMERGE: (FAIL)

• github identifies PR as mergeable -> PASS
• assigned to a milestone -> PASS
• 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 -> PASS
• Tested label found -> FAIL
• assigned to an approver -> FAIL
• approver count at least three -> FAIL