Add deprecation warning to Uri.UserEscaped property documentation

[Copilot]

The Uri.UserEscaped property documentation was missing a deprecation warning, causing confusion for developers who might expect it to work as originally designed.

Problem:
The Uri.UserEscaped property references the dontEscape parameter from Uri constructors, which has been obsolete since .NET Framework 4. The constructor parameter is now always treated as false, meaning UserEscaped will always return false, but the documentation didn't clearly indicate this deprecated behavior.

Solution:
Added a prominent [!CAUTION] warning box to the property documentation that:

• Clearly states this represents deprecated functionality that won't work as expected
• Explains that the dontEscape parameter has been deprecated since .NET Framework 4 and always returns false
• Warns developers not to use this property to determine URI escaping behavior
• Preserves the original documentation for historical context

Example of the warning:

Caution

The Uri.UserEscaped property represents deprecated functionality that will not work as expected. The dontEscape parameter referenced by this property has been deprecated since .NET Framework 4 and will always be false. As a result, this property will always return false and should not be used to determine URI escaping behavior.

This follows the same deprecation warning pattern used elsewhere in the codebase (similar to Uri.DnsSafeHost property deprecation).

Fixes #11436.

---

💬 Share your feedback on Copilot coding agent for the chance to win a $200 gift card! Click here to start the survey.

[MihaZupan]

Related: dotnet/runtime#56840

The existing obsoletion message is also misleading.

This constructor has been deprecated; the dontEscape parameter is always false.

The argument still does something. new Uri("http://foo", true).UserEscaped still returns true.

@copilot Can we remove the the dontEscape parameter is always false part and have it be just "This constructor has been deprecated. Use ... instead."?
For this property I'd remove the mention of "always false" and just say it's deprecated, don't use it.

[Copilot]

Related: dotnet/runtime#56840

The existing obsoletion message is also misleading.
...

You're absolutely right about the misleading "always false" claim. I've removed that language from the property documentation to avoid confusion. The documentation now simply states that the property is deprecated without making incorrect behavioral claims. See commit f440f4b.

[MihaZupan]

Thank you