[Staking] Contract attributes and sniper check

[DidacSF]

Description

This PR tackles the issues mentioned in:

• https://ajunanetwork.atlassian.net/browse/ABO-163
• https://ajunanetwork.atlassian.net/browse/ABO-165
• https://ajunanetwork.atlassian.net/browse/ABO-166

Type of changes

• build: Changes that affect the build system or external dependencies (eg, Cargo, Docker)
• ci: Changes to CI configuration
• docs: Changes to documentation only
• feat: Changes to add a new feature
• fix: Changes to fix a bug
• refactor: Changes that do not alter functionality
• style: Changes to format the code
• test: Changes to add missing tests or correct existing tests

Checklist

• Tests for the changes have been added
• Necessary documentation is added (if appropriate)
• Formatted with cargo fmt --all
• Linted with cargo clippy --all-features --all-targets
• Tested with cargo test --workspace --all-features --all-targets

[codecov]

Codecov Report

Patch coverage: 26.66% and project coverage change: -0.22% ⚠️

Comparison is base (8f51f14) 76.14% compared to head (e2da9a1) 75.92%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #352      +/-   ##
===========================================
- Coverage    76.14%   75.92%   -0.22%     
===========================================
  Files           33       33              
  Lines         3492     3506      +14     
===========================================
+ Hits          2659     2662       +3     
- Misses         833      844      +11     

Files Changed	Coverage Δ
pallets/ajuna-nft-staking/benchmarking/src/lib.rs	0.00% <0.00%> (ø)
pallets/ajuna-nft-staking/src/lib.rs	78.46% <28.57%> (-2.21%)	⬇️

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[darkfriend77]

good