[feat] inject env vars to launch options with steam format %command%

[silentrald]

Issue described in discord, blocked by #745

Notes:

• implemented a generic env parsers that is very similar to how steam handle theirs.
• also added generic error message that can be display generic error messages.

[silentrald]

@Zagrios can you check if "Could not properly parse the env var string." would fine for env parsing errors, before I go translating. Also check my test cases for parseEnvString should also suffice, or we can add more to handle some error cases as well.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Zagrios]

Looks good to me 👌

[Zagrios]

Thanks @silentrald ! ❤️
Merging 🎉