Refactor code related to CaptureWidget (#1801)

* Make CaptureWidget::initShortcuts uniform

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Disable window flags in debug builds

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Remove pointer in extendedRect parameter

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Move color initialization to the constructor

* Rename updateButtons to initButtons

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Rename handleButtonSignal to handleToolSignal

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Remove useless code in pixmap()

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Remove obsolete comment

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Move processTool definition inline

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Merge painter, aliasing and process into a function

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix inconsistent (non)usage of emit

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Rename nameID to type

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Remove some redundancy in confighandler.cpp

- In `getButtons`: instead of re-adding all the buttons manually, now
  the buttons are taken from
  `CaptureToolButton::getIterableButtonTypes()` and those we want
  unchecked are removed.
- Changed some parts to use `fromButtonToInt` instead of re-implementing
  it inline each time

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Revert "Disable window flags in debug builds"

This reverts commit 2adb583359bc0a1fd2d335f2d0e88299a4d1dd65.

* Disable window flags in debug builds

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>