Use Codestarts as default project generation tool

[ia3andy]

• Codestarts which only works alone are called "Singleton"
• Added checks to avoid conflict between Singelton codestarts
• Make codestart the default codegen and add a legacyCodegen flag
• Use RESTEasy example as default (commandmode example is not selectable for now.. until a picocli Create the Picocli Example codestart in Java & Kotlin #12633 example?)
• Update the guides with -DnoExamples when when relevent
• Update the tests

Fixes #12113

[ia3andy]

cc @maxandersen that gives you an idea of the PR

[aloubyansky]

Update the guides for compat by adding resteasy when relevent

What kind of compatibility? I understand that the plain resteasy extension isn't added in many cases now. My question is what kind of issue does it create?

[ia3andy]

Update the guides for compat by adding resteasy when relevent

What kind of compatibility? I understand that the plain resteasy extension isn't added in many cases now. My question is what kind of issue does it create?

Some of our guides instruction are based on the resteasy example, thus without it in the command extensions, it is not generated. Soon, we will have example for most extensions, then we will have to remove resteasy, and the example will directly be the appropriate one.. (like we just did with spring-web)

[ia3andy]

I am waiting for the result of this discussion to make the decided changes: https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/quarkus-dev/-j7C9UqYbF4/qyiTzQU5AAAJ

[ia3andy]

Sorry @aloubyansky this will need to be reviewed again. Since your approval, I've set resteasy as default and updated the docs and tests accordingly..

[gastaldi]

LGTM