Enforce backend and frontend names to be unique

[kuba00739]

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[c00kiemon5ter]

Suggested change

	raise SATOSAConfigurationError("The name " + backend.name + " is taken!")
	raise SATOSAConfigurationError("The backend name " + backend.name + " is already used.")

[c00kiemon5ter]

Suggested change

	raise SATOSAConfigurationError("The name " + frontend.name + " is taken!")
	raise SATOSAConfigurationError("The frontend name " + frontend.name + " is already used.")

[c00kiemon5ter]

I think it's good to have this.

However, this is doing the right thing but in the wrong way. We should introduce a configuration validation step where this kind of checks should be taking place. Ideally, we can have a configuration schema and check against that directly.

I don't mind merging this to help when these issues come up, but we should re-iterate to properly fix this and other configuration checks as a step in the loading process.