Fix 'Restart' RPC command

[m-seker]

Summary
restart RPC fails because execve doesn't return and blocks the process. Hence we don't return a response to the caller. Also, hyperion->freeObjects() is called on a totally wrong thread, which causes a crash.

This PR introduces a different path for restarting Hyperion. It starts a new instance of Hyperion in a detached state with a special internal command line argument (--wait-hyperion). New instance sees that --wait-hyperion argument is set and waits until previous Hyperion exits. Old instance gracefully quits application. Then new instance continues with normal execution.

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Docs
• Build-related changes
• Other, please describe:

If changing the UI of web configuration, please provide the before/after screenshot:

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact and migration path for existing setups:

The PR fulfills these requirements:

• When resolving a specific issue, it's referenced in the PR's body (e.g. Fixes: #xxx[,#xxx], where "xxx" is the issue number)

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature
• Related documents have been updated (docs/docs/en)
• Related tests have been updated

PLEASE DON'T FORGET TO ADD YOUR CHANGES TO CHANGELOG.MD

• Yes, CHANGELOG.md is also updated

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Other information:

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[tihoangyeudau]

You are the King of Fixing bugs!!!

[Paulchen-Panther]

Works wonderfully. Many thanks

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