[TwigComponent] Fix PreLexer confusing {# inside output expressions with comments

[Amoifr]

Q	A
Bug fix?	yes
New feature?	no
Deprecations?	no
Issues	Fix #3514
License	MIT

The TwigPreLexer was treating any {# it encountered as the opening of a Twig comment, even when that {# actually lived inside a Twig output expression (e.g. inside a string literal passed to |trans). When the matching #} was missing — typically the case for ICU MessageFormat plural strings like {count, plural, one {# item} other {# items}} — the lexer consumed the rest of the template as a fake comment, swallowing any <twig:…> tags after it.

This PR adds a top-level handler for {{ … }} in the PreLexer's main loop. The new helper consumeTwigExpressionContent() walks the expression body with string-literal awareness (single quotes, double quotes, \\-escapes), so that }} or {# appearing inside a string don't end the expression early or trigger comment mode. The implicit {% block content %} injection still kicks in when the expression appears as content inside a component.

5 regression tests added covering:

• the original ICU plural example from the issue
• }} inside a string literal in {{ … }}
• {#…#} inside a double-quoted string
• escaped quotes inside the expression
• {{ … }} inside a component (default-block injection)

Marking as draft pending @Kocal's input on the scope question raised in #3514: should this same protection be extended to {% … %} (where {% set foo = '{# bar #}' %} has the same latent issue), or kept focused on {{ … }} ?