Set FullRelayoutNeeded after GetNaturalSize/GetHeightForWidth to avoid the backup...

Set FullRelayoutNeeded after GetNaturalSize/GetHeightForWidth to avoid the backup/restore of fields in visual-model.

This solved some issues happen after calling GetNaturalSize/GetHeightForWidth or after initialization when set WIDTH_RESIZE_POLICY to ResizePolicy::USE_NATURAL_SIZE

1) Fixing the issue where characters were being drawn at the same location whenever GetNaturalSize was called.
https://review.tizen.org/gerrit/c/platform/core/uifw/dali-toolkit/+/253286
2) Side effect on Scrolling, LineWrap and Invalid position of cursor in TextEditor after calling GetNaturalSize or GetHeightForWidth.
https://review.tizen.org/gerrit/c/platform/core/uifw/dali-toolkit/+/255379
3) Crash issue when set WIDTH_RESIZE_POLICY to ResizePolicy::USE_NATURAL_SIZE in TextEditor then insert/remove characters from 2nd line in it after initialization
4) Crash issue when set WIDTH_RESIZE_POLICY to ResizePolicy::USE_NATURAL_SIZE in TextEditor and select_text at initialization then cut it after initialization
5) Crash issue when set WIDTH_RESIZE_POLICY to ResizePolicy::USE_NATURAL_SIZE in TextEditor then double enter in it after initialization
6) Incorrect NaturalSize after the second call for GetNaturalSize. This issue in TextLabel when call GetNaturalSize, then set MULTI_LINE, then re-call GetNaturalSize with Text has break-line

Change-Id: Ieea984f41a218c62e016baa60156b51e985f2fc0