Enable staking: Babe, small refactoring

[borispovod]

• [x] use BABE instead of Aura
• [x] inflation
• [x] slashing
• [x] staking (pallet, configs)
• [x] tests

[coveralls]

Pull Request Test Coverage Report for Build 1105717755

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 64.912%

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Totals
Change from base Build 1102196571:	0.0%
Covered Lines:	79
Relevant Lines:	92

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💛 - Coveralls

[borispovod]

@fzzr- See how i disabled warning in external macro using -A non_fmt_panic

[borispovod]

We should review moonbeam staking before merge