Reply rendering (#861)

* Cleanup how we use message timeline items in preparation for rich reply rendering

* Expose reply details up to the UI level

* Render replies in the timeline (textual for now). Remove now unused AttributedStringBuilderComponent isReply flag.

* Move reply detail loading to when the item appears instead of when it's created.

* Fix unit tests

* Fetch event details also when the reply details are in the error state

* Tweaks following code review

* Localise emote bodies

* Fix replies not loading sometimes, use the current event identifier instead of the one being replied to

UnitTests/Sources/AttributedStringBuilderTests.swift

@@ -341,7 +341,6 @@ class AttributedStringBuilderTests: XCTestCase {
         }
         
         XCTAssertTrue(component.isBlockquote, "The reply quote should be a blockquote.")
-        XCTAssertTrue(component.isReply, "The reply quote should be detected as a reply")
     }
     
     func testMultipleGroupedBlockquotes() {
@@ -388,9 +387,6 @@ class AttributedStringBuilderTests: XCTestCase {
         let coalescedComponents = attributedString.formattedComponents
         
         XCTAssertEqual(coalescedComponents.count, 6)
-        for component in coalescedComponents where component.isReply {
-            XCTFail("None of the blockquotes should be detected as replies.")
-        }
         
         var numberOfBlockquotes = 0
         for run in attributedString.runs where run.elementX.blockquote ?? false && run.link != nil {