[BridgeJS] Optionals cause build error with Embedded Swift

[sliemeobn]

Optionals seem broken when built for Embedded (with recent 6.3 Embedded SDK)

eg:

@JSSetter public func setTextContent(_ value: String?) throws(JSException)
// or
@JSSetter public func setOnfinish(_ callback: JSObject?) throws(JSException)

build fine for "full Swift" but fail to compile for Embedded

/Users/simon/dev/elementary-swift/elementary-ui/Sources/BrowserInterop/Generated/BridgeJS.swift:411:29: error: cannot use conformance of 'Optional<Wrapped>' to '_BridgedAsOptional' here; the conformance is declared as SPI in 'JavaScriptKit'
 409 |         throw error
 410 |     }
 411 |     return Optional<String>.bridgeJSLiftReturnFromSideChannel()
     |                             `- error: cannot use conformance of 'Optional<Wrapped>' to '_BridgedAsOptional' here; the conformance is declared as SPI in 'JavaScriptKit'
 412 | }
 413 | 

/Users/simon/dev/elementary-swift/elementary-ui/Sources/BrowserInterop/Generated/BridgeJS.swift:642:29: error: cannot use conformance of 'Optional<Wrapped>' to '_BridgedAsOptional' here; the conformance is declared as SPI in 'JavaScriptKit'
 640 |         throw error
 641 |     }
 642 |     return Optional<String>.bridgeJSLiftReturnFromSideChannel()
     |                             `- error: cannot use conformance of 'Optional<Wrapped>' to '_BridgedAsOptional' here; the conformance is declared as SPI in 'JavaScriptKit'
 643 | }
 644 | 

/Users/simon/dev/elementary-swift/elementary-ui/Sources/BrowserInterop/Generated/BridgeJS.swift:1047:52: error: cannot use conformance of 'Optional<Wrapped>' to '_BridgedAsOptional' here; the conformance is declared as SPI in 'JavaScriptKit'
1045 | func _$JSAnimation_onfinish_set(_ self: JSObject, _ newValue: JSObject?) throws(JSException) {
1046 |     let selfValue = self.bridgeJSLowerParameter()
1047 |     let (newValueIsSome, newValueValue) = newValue.bridgeJSLowerParameter()
     |                                                    `- error: cannot use conformance of 'Optional<Wrapped>' to '_BridgedAsOptional' here; the conformance is declared as SPI in 'JavaScriptKit'
1048 |     bjs_JSAnimation_onfinish_set(selfValue, newValueIsSome, newValueValue)
1049 |     if let error = _swift_js_take_exception() {

/Users/simon/dev/elementary-swift/elementary-ui/Sources/BrowserInterop/Generated/BridgeJS.swift:1557:29: error: cannot use conformance of 'Optional<Wrapped>' to '_BridgedAsOptional' here; the conformance is declared as SPI in 'JavaScriptKit'
1555 |         throw error
1556 |     }
1557 |     return Optional<String>.bridgeJSLiftReturnFromSideChannel()
     |                             `- error: cannot use conformance of 'Optional<Wrapped>' to '_BridgedAsOptional' here; the conformance is declared as SPI in 'JavaScriptKit'
1558 | }
1559 |