Fix compiler warnings related to nullability in Devices module

[NikolaVetnic]

Readiness checklist

• I added/updated unit tests.
• I added/updated integration tests.
• I ensured that the PR title is good enough for the changelog.
• I labeled the PR.

Description

Various code issues and warnings related to null values found using the ReSharper tool in the Devices module were investigated and addressed.

Summary by CodeRabbit

• New Features

  • Enabled nullable reference types across various modules to enhance code safety and nullability checks.
  • Streamlined logic for database seeding and improved code clarity in several areas.
  • Added checks for the existence of certain objects before proceeding with operations to avoid potential errors.
  • Simplified the creation and handling of DTOs and commands by marking properties as required, ensuring necessary data is provided by consumers.

• Bug Fixes

  • Corrected a typo and handled nullable types more effectively in command handlers.
  • Fixed method signatures to support nullable reference types, aligning with the enabled nullable context.
  • Removed outdated and commented-out test scenarios, focusing on relevant test cases.

• Refactor

  • Refined method signatures for transactional operations to improve the handling of database transactions.
  • Updated various command and DTO classes to require certain properties, ensuring critical information is always included.
  • Streamlined the logic in several areas, including database seeding, to improve performance and readability.

• Chores

  • Removed unnecessary namespace imports and adjusted configuration settings to clean up the codebase.
  • Conditionally added services based on options, improving the modularity and configurability of the system.

[tnotheis]

Ah, I need to check one more thing