TYPO3.TypoScript

[!!!][FEATURE] Add @position support to Case TypoScript object and introduce explicit Matcher

With I3d2947e998dfc61e2503f433ef12588d5a15f0f3, we introduced an explicit @position for
TypoScript Arrays. With this change, the same functionality is possible for the Case TypoScript
object.

Additionally, matchers are now directly added as sub-objects of the Case TypoScript object, not
using the "matchers" sub-key anymore.

Example before:

someCase = Case {
        matchers.10.condition = ${/* condition here /}
        matchers.10.type = 'MyType'
        matchers.20.condition = ${/ another condition */}
        matchers.20.type = 'MyOtherType'
    }

Example now:

someCase = Case {
        myTypeCondition.condition = ${/* condition here /}
        myTypeCondition.type = 'MyType'
        myTypeCondition.@position = 10
        myOtherTypeCondition.condition = ${/ another condition */}
        myOtherTypeCondition.type = 'MyOtherType'
        myOtherTypeCondition.@position = 20
    }

Of course, the old numerically-indexed variant still works as fallback if @position is not specified.
You can also specify @position with "start", "end" and priorities, as in TypoScript arrays.

Furthermore, an extra TypoScript object for the Matcher has been implemented, which is used internally.
This enables functionality such as modifying the TypoScript context inside a certain matcher, or
using TypoScript prototypes for this:

someCase = Case {
        prototype(TYPO3.TypoScript:Matcher) {
            @override.myOtherVariable = 'test2'
        }

myTypeCondition {
            condition = ${/* condition here */}
            type = 'MyType'
            @override.myNewVariable = 'test'
        }
    }

In the example above, both myOtherVariable and myNewVariable are available when rendering MyType
through the condition.

Backwards Compatibility =======================

We still support the old "matchers.*" syntax for a limited time; but you should take time and re-write
it to the new syntax.

Breaking Change ===============

This change is still breaking because it needs a new TypoScript object "TYPO3.TypoScript:Matcher"
registered. Thus, your TypoScript needs at least to include the following line:

prototype(TYPO3.TypoScript:Matcher).implementationClassName = 'TYPO3\\TypoScript\\TypoScriptObjects\\Matcher'

For Phoenix, we can include the line in the default TypoScript, effectively making the change non-breaking for
our users.

Related: #39658
Change-Id: Ie70394fe7149e63deb661a22eac6445c0d66ac56