fix: escape all Unicode curly/smart quotes in PowerShell double-quoted strings (closes #10123)

What does this MR do?

Adds backtick escaping for 4 previously-unescaped Unicode curly/smart quote characters in psDoubleQuote: U+2018, U+2019, U+201A, U+201B. Three double-quote variants (U+201C, U+201D, U+201E) were already escaped.

Why was this MR needed?

PowerShell's parser treats Unicode curly/smart quote characters as string delimiters inside double-quoted strings. CI variable values containing these characters cause UnexpectedToken parser errors.

What's the best way to test this MR?

Set a CI variable containing one of the added characters (e.g. O'Connor with U+2019) and verify a PowerShell job succeeds instead of failing with a parser error.

What are the relevant issue numbers?

Closes #10123