Add NuGet lock file and enable locked CI package restore

[albertospelta]

This pull request introduces package lock file support to the project, ensuring more reliable and repeatable builds by locking dependency versions. It also adds configuration to optimize builds in continuous integration environments, and removes an unused property group from the project file.

Dependency management improvements:

• Added a new src/packages.lock.json file to lock all NuGet package versions for the project, ensuring consistent restores across environments.
• Enabled NuGet package restore lock file by setting RestorePackagesWithLockFile to true in Bravo.csproj.

Continuous integration optimizations:

• Added CI-specific properties to Bravo.csproj (RestoreLockedMode and ContinuousIntegrationBuild) to improve reliability and performance of builds on CI servers.

Project file cleanup:

• Removed a commented-out property group related to NuGet restore sources from Bravo.csproj to clean up the file.