Update & improve Cadence onboarding tutorials and best practices docs

Context

The Cadence tutorials (e.g. https://docs.onflow.org/cadence/tutorial/01-first-steps) were originally written almost a year ago. Cadence has changed a lot since then! It's time to update them to be demonstrative of modern Cadence.

Definition of Done

The following should be addressed for each tutorial listed below:

• Code is updated to be compatible with the latest Cadence version (syntax errors and semantic errors are corrected)
• Code is updated to better demonstrate idiomatic Cadence (when applicable)
• Where needed, tutorial instructions are updated for clarity or to remove outdated references

Tutorials:

• Hello World
• Fungible Tokens
• Non-Fungible Tokens
• Marketplace Setup
• Marketplace
• Composable Resources
• Voting