adds input parameters validation

[baywet]

• adds validation for language, loglevel, namespace and class name parameters
• adds shorthand for loglevel and description parameters
• adds validation for path parameters

fixes #127

[baywet]

For information there's no diff in terms or generation.
This PR brings more user friendly messages like:

• Could not open/create output directory X:\oinoinoin, reason: Could not find a part of the path 'X:\oinoinoin'.
• Could not open the file at C:\sources\github\kiota\src\kiota\openapi.yml, reason Could not find file 'C:\sources\github\kiota\src\kiota\openapi.yml'.
• ruby is not a supported generation language, supported values are CSharp, Java, TypeScript, PHP, Python, Go
• dangerousis not a supported generation log level, supported values are Trace, Debug, Information, Warning, Error, Critical, None
• ,charp is not a valid class name for the client, the class name must conform to ^[a-zA-Z_][\w_-]+
• ,charp is not a valid namespace name for the client, the namespace name must conform to ^[a-zA-Z_][\w._-]+

Instead of throwing exceptions at people.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

97.7% Coverage
0.0% Duplication