Get Serial Scenarios from the front of the queue in runner::Basic

[ilslv]

Synopsis

If Feature has Serial Scenarios, both them and Concurrent ones are inserted in front. But when we get them, Concurrent Scenarios are drained from the front, while Serial Scenarios are popped from the back.
This may lead console output hanging because of executing wrong Concurrent Scenarios.

Solution

Get Serial Scenarios from the front, same as Concurrent.

Checklist

• Created PR:
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  • Name contains Draft: prefix
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  • Has assignee
• Documentation is updated (if required)
• Tests are updated (if required)
• Changes conform code style
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• Review is completed and changes are approved
• Before merge:
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  • Draft: prefix is removed
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This PR is nominated at RU RustCon Contest

[ilslv]

FCM

Get `Serial` `Scenario`s from the front of the queue in `runner::Basic` (#146)