stages/identification: add captcha to identification stage (#11711)

* add captcha to identification stage

* simplify component invocations

* fail fast on `onTokenChange` default behavior

* reword docs

* rename `token` to `captcha_token` in Identification stage contexts

(In Captcha stage contexts the name `token` seems well-scoped.)

* use `nothing` instead of ``` html`` ```

* remove rendered Captcha component from document flow on Identification stages

Note: this doesn't remove the captcha itself, if interactive, only the loading
indicator.

* add invisible requirement to captcha on Identification stage

* stylize docs

* add friendlier error messages to Captcha stage

* fix tests

* make captcha error messages even friendlier

* add test case to retriable captcha

* use default

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

---------

Signed-off-by: Jens Langhammer <jens@goauthentik.io>
Co-authored-by: Jens Langhammer <jens@goauthentik.io>

blueprints/schema.json

@@ -10679,6 +10679,11 @@
                     "title": "Password stage",
                     "description": "When set, shows a password field, instead of showing the password field as separate step."
                 },
+                "captcha_stage": {
+                    "type": "integer",
+                    "title": "Captcha stage",
+                    "description": "When set, adds functionality exactly like a Captcha stage, but baked into the Identification stage."
+                },
                 "case_insensitive_matching": {
                     "type": "boolean",
                     "title": "Case insensitive matching",