Add authorize() DSL method that accepts HttpMethod

[adamu]

Attempted an implementation for #8307, which adds an implementation of authorize() for AuthorizeRequestsDsl, so that we can write code like this:

http {
    authorizeRequests {
        authorize(GET, "/path", permitAll)
        authorize(PUT, "/path", denyAll)
    }
}

[eleftherias]

Thanks for the PR @adamu.

There are some nice changes here that are not directly related to the reported issue.
It would be best if those changes were in separate commits to give a clearer picture to someone viewing the commit history.

One example is extracting PATTERN_TYPE.

Another example is using named arguments. While this is necessary given the changes to PatternAuthorizationRule it may not be obvious to someone viewing the history of this file.

I can see this broken into 3 commits, example titles
"Extract pattern type in request matcher DSL"
"Use named arguments in Kotlin authorization rule"
"Add authorize() DSL method that accepts HttpMethod"

All commits can still be part of this PR.

I have also left a few comments inline.

[adamu]

@eleftherias I have split the PR into 3 commits, using your suggested titles.

I also added the extra test.

However, there is some behaviour I am unsure about. For AuthorizeRequestsByMvcConfigWithAndWithoutHttpMethod:

http {
    authorizeRequests {
        authorize("/no_specified_method", permitAll)
        authorize(HttpMethod.GET, "/specified_method", permitAll)
        authorize(HttpMethod.PUT, "/specified_method", denyAll)
    }
}

With this spec, even though /no_specified_method is mapped with a @RequestMapping, a PUT request to /no_specified_method will result in a 403 error.

Additionally, if we change the spec for /specified_method so that the PUT is permitted and GET is denied, the PUT request will be denied.

I think this is the behaviour of MvcMatchersAuthorizedUrl and is not directly related to the behaviour of this DSL, but I wanted to mention it.

[eleftherias]

Thanks for the updates @adamu.

The PUT behaviour that you mentioned occurs because the request does not include a CSRF token.
I have added an inline comment showing how to add the CSRF token.

One more note about the commits, please add Fixes: gh-8307 to the final commit.
This will associate the commit with the reported issue and also close the issue when the commit is merged.
See the contributing guidelines for more details

[adamu]

@eleftherias I have made the following changes:

1. Added the HttpMethod for the antMatchers() too.
2. Added a corresponding test for that.
3. Added the servlet path test..

Travis failed, but it seems to be due to style problems in CONTRIBUTING.adoc, which I've not changed in this PR (← Resolved in 2eebfd3).

[eleftherias]

Thanks @adamu! I have left some more comments inline.

[eleftherias]

Thank you for all your work @adamu.
I have one more comment and then we should be ready to merge.

[eleftherias]

Thanks again @adamu!
This is now merged into master.