feat (jans-cedarling): Add Bootstrap property for JWKS

[nynymike]

Instead of downloading the JWKS from the jwks_endpoint, it would be helpful in some cases if we could provide a bootstrap property to specify the jwks file.

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Test cases and code coverage

• Write unit test to cover added/changed code
• Update integration tests to cover added/changed code

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Document the changes

• task for updating user guides if needed
• task for updating installation and configuration guides if needed
• task for updating developer documentation if needed
• task for updating technical documentation if needed