feat: add PKCE support for OAuth2 Authorization Code flows (#5361)

* Add PKCE support.

* Fix tests

* Update oauth2.md

* Rename usePkce

* Fix the BrokenComponent error

* Update oauth2.md

* Remove isCode variable. Remove uuid4 dependency.

* Remove utils functions

* Import crypto

* Fix tests

* Fix the tests

* Cleanup

* Fix code_challenge generation

* Move code challenge and verifier to utils for mocks. Update tests.

* Mock the PKCE methods in the utils file properly.

* Add missing expect

* use target-method spies

* Add comments to explain test values.

* Get rid of jsrsasign.

test/mocha/docker/oauth.js

@@ -23,6 +23,7 @@ describe("docker: env translator - oauth block", function() {
       OAUTH_APP_NAME: ``,
       OAUTH_SCOPE_SEPARATOR: "",
       OAUTH_ADDITIONAL_PARAMS: ``,
+      OAUTH_USE_PKCE: false
     }
 
     expect(oauthBlockBuilder(input)).toEqual(dedent(`
@@ -33,8 +34,10 @@ describe("docker: env translator - oauth block", function() {
       appName: "",
       scopeSeparator: "",
       additionalQueryStringParams: undefined,
+      usePkceWithAuthorizationCodeGrant: false,
     })`))
   })
+
   it("should generate a full block", function() {
     const input = {
       OAUTH_CLIENT_ID: `myId`,
@@ -43,6 +46,7 @@ describe("docker: env translator - oauth block", function() {
       OAUTH_APP_NAME: `myAppName`,
       OAUTH_SCOPE_SEPARATOR: "%21",
       OAUTH_ADDITIONAL_PARAMS: `{ "a": 1234, "b": "stuff" }`,
+      OAUTH_USE_PKCE: true
     }
 
     expect(oauthBlockBuilder(input)).toEqual(dedent(`
@@ -53,6 +57,7 @@ describe("docker: env translator - oauth block", function() {
       appName: "myAppName",
       scopeSeparator: "%21",
       additionalQueryStringParams: { "a": 1234, "b": "stuff" },
+      usePkceWithAuthorizationCodeGrant: true,
     })`))
   })
 })