Fixes for Edit Style Dialog

[cbjeukendrup]

• Resolves: https://trello.com/c/DE9tYdOL/97-style-dialog-shows-wrong-tab-in-left-column-upon-opening
  Fix left column of Edit Style Dialog being not up-to-date
  When you right-clicked an item and chose 'Style…', the Style Dialog would show the correct page, but the left page still showed the first row selected. That is now fixed.

• Resolves: https://trello.com/c/trG7Eihi/96-wrong-behavior-of-cancel-and-esc-in-style-dialog = https://musescore.org/en/node/315054
  Fix #315054: Fix behavior of Esc key in Style Dialog

• Temporarily resolves: https://trello.com/c/tFasP1lX/95-style-dialog-does-not-update-when-score-is-changed-shows-wrong-settings = https://musescore.org/en/node/315050
  Temporary fix #315050: Show Edit Style Dialog modally, to prevent problems
  Actually reverts PR Fix #302990: Set Style Edit dialog to be non-modal to allow score traversal when s… #6845, because getting this to work properly would require quite a lot of refactoring.

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