Add UI for image-attachment "focus" (#2620)

* Attempt-zero implementation of a "focus" feature for image attachments. Choose "Set focus" in the attachment menu, tap once to select focus point (no visual feedback currently), tap "OK". Works in tests.

* Remove code duplication between 'update description' and 'update focus'

* Fix ktlint/bitrise failures

* Make updateMediaItem private

* When focus is set on a post attachment the preview focuses correctly. ProgressImageView now inherits from MediaPreviewImageView.

* Replace use of PointF for Focus where focus is represented, fix ktlint

* Substitute 'focus' for 'focus point' in strings

* First attempt draw focus point. Only updates on initial load. Modeled on code from RoundedCorners builtin from Glide

* Redraw focus after each tap

* Dark curtain where focus isn't (now looks like mastosoc)

* Correct ktlint for FocusDialog

* draft: switch to overlay for focus indicator

* Draw focus circle, but ImageView and FocusIndicatorView seem to share a single canvas

* Switch focus circle to path approach

* Correctly scale, save and load focuses. Clamp to visible area. Focus editor looks and feels right

* ktlint fixes and comments

* Focus indicator drawing should use device-independent pixels

* Shrink focus window when it gets unattractively tall (no linting, misbehaves on wide aspect ratio screens)

* Correct max-height behavior for screens in landscape mode

* Focus attachment result is are flipped on x axis; fix this

* Correctly thread focus through on scheduled posts, redrafted posts, and drafts (but draft focus is lost on post)

* More focus ktlint fixes

* Fix specific case where a draft is given a focus, then deleted, then posted in that order

* Fix accidental file change in focus PR

* ktLint fix

* Fix property style warnings in focus

* Fix remaining style warnings from focus PR

Co-authored-by: Conny Duck <k.pozniak@gmx.at>

app/src/main/java/com/keylesspalace/tusky/db/DraftEntity.kt

@@ -22,6 +22,7 @@ import androidx.room.Entity
 import androidx.room.PrimaryKey
 import androidx.room.TypeConverters
 import com.google.gson.annotations.SerializedName
+import com.keylesspalace.tusky.entity.Attachment
 import com.keylesspalace.tusky.entity.NewPoll
 import com.keylesspalace.tusky.entity.Status
 import kotlinx.parcelize.Parcelize
@@ -52,6 +53,7 @@ data class DraftEntity(
 data class DraftAttachment(
     @SerializedName(value = "uriString", alternate = ["e", "i"]) val uriString: String,
     @SerializedName(value = "description", alternate = ["f", "j"]) val description: String?,
+    @SerializedName(value = "focus") val focus: Attachment.Focus?,
     @SerializedName(value = "type", alternate = ["g", "k"]) val type: Type
 ) : Parcelable {
     val uri: Uri