[java][spring] added springdoc support for service metadata and security

[bluenick2k17]

• Added the auto-generated OpenAPI 3 support for service metadata and security, using springdoc.
  • Changes made to SpringCodegen to add the new documentation config file (SpringDocConfiguration.java) to the list of auto-generated files
  • Added new template file: springdocDocumentationProvider.mustache for the Spring generator which builds SpringDocConfiguration.java
  • This can be validated by generating a java spring API using the default documentation provider, and examining target/generated-sources/openapi/src/main/java/org/openapitools/configuration/SpringDocConfiguration.java in the resulting API.
  • Updated spring samples in this PR can also be checked to see some examples of the new springdoc configuration files.
• CodegenSecurityTest was updated to test the new addition of the SpringDoc configuration, and test was cleaned up to reduce duplication when adding the additional documentation provider test.
• Fixed a piece of documentation and the connected code in SpringCodegen which still used Springfox verbiage, even though the default documentation provider is springdoc.

Some notes on the implementation:

• Did not remove Springfox, since it's marked for removal in 7.0.0: [Announcement] Deprecation Warnings for the Java/Spring Generator #11553
• Current pull request supports basic and API key fully with the security info. Does not yet support Oauth2 completely since it would require a bunch more work into the template. Would affect the ability to use auth on the swagger-ui with Oauth2
• CodegenSecurity doesn't support a description field yet for the auth method, so as of now that support remains the same

Closes #12220

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@cachescrubber (2022/02) @welshm (2022/02) @MelleD (2022/02) @atextor (2022/02) @manedev79 (2022/02) @javisst (2022/02) @borsch (2022/02) @banlevente (2022/02)

[welshm]

Thanks for adding this!

[wing328]

Thanks again for the PR, which has been included in the v6.0.0 release: https://twitter.com/oas_generator/status/1529669733934841856