feat: allow numeric input for Content-Format and Accept options

[JKRhb]

This PR introduces the possibility of passing numeric Content-Formats as option values to the setHeader method and adjusts the allowed request parameters.

[coveralls]

Pull Request Test Coverage Report for Build 3850969466

• 17 of 19 (89.47%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.1%) to 91.719%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/option_converter.ts	17	19	89.47%
<!--	Total:	17	19	89.47%	-->

Totals
Change from base Build 3820725058:	-0.1%
Covered Lines:	2854
Relevant Lines:	3069

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 3852188808

• 27 of 27 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.05%) to 91.903%

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Totals
Change from base Build 3820725058:	0.05%
Covered Lines:	2866
Relevant Lines:	3077

---

💛 - Coveralls

[Apollon77]

All fine, ok for me to merge