refactor: make definitionPathsToGenerateFrom option required

[toomuchdesign]

What kind of change does this PR introduce?

Refactor

What is the current behaviour?

Quite easy to forget to provide a definitionPathsToGenerateFrom, which results into not generating schemas silently

What is the new behaviour?

Make definitionPathsToGenerateFrom required and log a warning when empty.

Does this PR introduce a breaking change?

What changes might users need to make in their application due to this PR?

Other information:

Please check if the PR fulfills these requirements:

• Tests for the changes have been added
• Docs have been added / updated
• Relevant Changeset has been added

[changeset-bot]

🦋 Changeset detected

Latest commit: b45d4f3

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
openapi-ts-json-schema	Minor

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[github-actions]

Pull Request Test Coverage Report for Build 5609870725

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.3%) to 98.077%

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Totals
Change from base Build 5604916749:	0.3%
Covered Lines:	35
Relevant Lines:	35

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💛 - Coveralls