Validate CLI user input

[Shinigami92]

Is your feature request related to a problem? Please describe.

No user-entered values are currently being checked or validated during parsing
This can lead to undesirable behavior

Describe the solution you'd like

Check user input that can be passed via CLI options

Additional context

While working on #489 several problems were found and some TODOs were added

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HTMLHint/src/cli/htmlhint.ts

Lines 100 to 101 in 1f1f448

	rulesdir: program.rulesdir,
	ruleset: program.rules,

• rulesdir needs to be a valid string and path
• rules needs to be a valid string and must be parsed to ruleset
• config needs to be a valid string and path

all values are optional