fix: rename policy packages to now policy

[Marc-André Moreau (mamoreau-devolutions)]

Summary

• rename the .NET policy package/project/namespace to Devolutions.NowPolicy
• rename the Rust policy crate to now-policy and update crate imports/generator binary
• update CI, xtask paths, Cargo.lock, and policy docs for the new naming
• keep policy wire-format identifiers unchanged (PackageBrokerPolicy and broker-policy schema URI)

Validation

• cargo test -p now-policy
• dotnet test policies/dotnet/Devolutions.NowPolicy.slnx
• dotnet format policies/dotnet/Devolutions.NowPolicy.slnx --verify-no-changes
• git diff --cached --check

[Vladyslav Nikonov (vnikonov-devolutions)]

Should we also rename schema url?

https://devolutions.net/schemas/broker-policy.schema.1.0.json
->
https://devolutions.net/schemas/now-policy.schema.1.0.json