Fix unhandled synchronous throw from WebSocket ConnectAsync (#15783) (#…

…15788)

* Fix unhandled synchronous throw from ConnectAsync

(Generated summary)
ConnectAsync can throw synchronously (e.g. WININET_E_INVALID_CA /
0x80072EE1 on certificate validation failure) before returning an
IAsyncAction. Move the call inside the existing try/catch block so
such exceptions are routed through Fail() instead of propagating
unhandled. Add ConnectAsyncThrowsSynchronously unit test to cover
this path.

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probe tag 141354675

probe tag 141352166

probe tag 629004