refactor(snap)!: Drop the support for legacy snap env options

[farshidtz]

• Drop the support for legacy snap options with env. prefix
• Upgrade edgex-snap-hooks to v3
• Upgrade edgex-snap-testing Github action to v3
• Add snap's Go module to dependabot
• Other minor refactoring

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Testing Instructions

New Dependency Instructions (If applicable)

[MonicaisHer]

@farshidtz Thank you, looks good!