Backport #10963 and #10997 to rel/4.4

[Amaury Levé (Evangelink)]

Backport of #10963 and #10997 to rel/4.4.

• preserves original response-file arguments while exposing expanded arguments to Retry relaunches;
• regenerates and cleans per-attempt response files while retaining command-line length handling;
• preserves sensitive-value redaction across nested response files and reports the failing nested file;
• covers response-file layouts, delimiter forms, recursion rejection, cleanup, and nested redaction.

Validation:

• affected platform and Retry extension projects build successfully with 0 warnings and 0 errors (artifacts/log/Debug/Build.binlog);
• 76 targeted Microsoft.Testing.Platform.UnitTests passed;
• 82 targeted Microsoft.Testing.Extensions.UnitTests passed.