[PHP/Dart/Python] Correctly escape strings in single quotes (Fixes #17582)

[JulianVennen]

This PR fixes #17582 by correctly escaping strings inside the single quotes for the PHP, Dart and Python generators.
For the PHP generator, double quotes escaped by the default generator are unescaped because PHP treats '\"' as a string containing a backslash and a double quote.
I have verified that python and dart treat '\"' as a string containing just a double quote character.

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[wing328]

in abstract typescript codegen, it overrides escapeText to replace ' with \\'

openapi-generator/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractTypeScriptClientCodegen.java

Line 1068 in e914c40

public String escapeText(String input) {

what about follow the same without introducing escapeTextInSingleQuotes?

[JulianVennen]

There are several issues with escaping single quotes by default that would also affect other generators:

• Some languages (e.g., PHP) treat '\"' as a string containing a backslash and a double quote
• ' is often used in text like parameter descriptions and would be escaped in comments, which leads to doc blocks like this:
  
• Escaping a single quote is illegal in some formats (e.g., JSON)

Ideally, the context a text is used in (e.g., JSON, single-quoted string, double-quoted string or comment) could be taken into account when a string is escaped, either by making them individual methods or by adding a parameter for that.

[wing328]

thanks for the explanation. let me think about it and review accordingly

[wing328]

thanks again for the PR

let's give it a try