Replace detached tasks with Task.dispatch(on:) (#201)

* Use Task.detach(on:) everywhere that was blocking.
* Don't wrap the continuations in a Task 🤦‍♂️
* Add sendable requirement to closure.

ElementX/Sources/Other/HTMLParsing/AttributedStringBuilder.swift

@@ -23,9 +23,9 @@ struct AttributedStringBuilder: AttributedStringBuilderProtocol {
     private let linkColor = UIColor.blue
     
     func fromPlain(_ string: String?) async -> AttributedString? {
-        await Task.detached {
+        await Task.dispatch(on: .global()) {
             fromPlain(string)
-        }.value
+        }
     }
     
     func fromPlain(_ string: String?) -> AttributedString? {
@@ -41,9 +41,9 @@ struct AttributedStringBuilder: AttributedStringBuilderProtocol {
     }
     
     func fromHTML(_ htmlString: String?) async -> AttributedString? {
-        await Task.detached {
+        await Task.dispatch(on: .global()) {
             fromHTML(htmlString)
-        }.value
+        }
     }
     
     // Do not use the default HTML renderer of NSAttributedString because this method