[!!!][TASK] Remove POST option from typolink.addQueryString.method

Setting `addQueryString.method` of typolink could be used like shown
below in order to transform HTTP POST parameters into according GET
parameters.

    typolink {
        parameter = 123
        addQueryString = 1
        addQueryString.method = POST
    }

In terms of correctly using HTTP verbs it's bad practise in general
to treat GET and POST equally, besides that documentation already
mentioned potential side-effects like accidentally exposing sensitive
data submitted via POST to proxies or log files.

That's why values POST, GET,POST and POST,GET are not allowed anymore
for `typolink.addQueryString.method`. Maintaining functionality - if
required at all - has to be done using domain specific logic in
according controllers or middleware implementations.

Resolves: #88755
Releases: master
Change-Id: I6ecfdd2ee98251b64093c1a13f9371beea862ddd
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/61295


Tested-by: Benjamin Franzke <bfr@qbus.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>