Move markdown parsing to list creating stage

...g/futo/circles/feature/timeline/TimelineDialogFragment.kt

...org/futo/circles/feature/timeline/list/TimelineAdapter.kt

.../futo/circles/feature/timeline/list/TimelineViewHolder.kt

...o/circles/feature/timeline/post/menu/PostMenuViewModel.kt

.../org/futo/circles/core/feature/markdown/MarkdownParser.kt

...es/core/feature/markdown/mentions/plugin/MentionPlugin.kt

...cles/core/feature/timeline/builder/BaseTimelineBuilder.kt

...les/core/feature/timeline/builder/MultiTimelineBuilder.kt

...es/core/feature/timeline/builder/SingleTimelineBuilder.kt

.../org/futo/circles/core/mapping/MediaPostContentMapping.kt

...a/org/futo/circles/core/mapping/TextPostContentMapping.kt

...ava/org/futo/circles/core/mapping/TimelineEventMapping.kt

core/src/main/java/org/futo/circles/core/model/Post.kt

.../src/main/java/org/futo/circles/core/model/PostContent.kt

core/src/main/java/org/futo/circles/core/model/PostInfo.kt