[CHARMAP] Functionality Improvements and Bug Fixes (#2560)

[CHARMAP] Functionality Improvements and Bug Fixes (#2560)

- Resize the window slightly when compiled with REMOVE_ADVANCED to avoid deadspace at the bottom of the window.

- Skip over the non-printable characters by starting with character ' ' + 1.

- Instead of iterating over every cell, simply compute the cell x and y using the CellSize.

- Modify behaviour of charmap to allow large character render on mouse move, only hiding the larger character on double click.

- Simplify math for moving window to be on desktop.
Added FIXME to highlight this doesn't work well on multi-monitor setups.
Changed xPos and yPos to LONG since negative numbers are valid on multi-monitor setups.

- Do not draw invalid glyphs on the map (can happen when switching fonts or filtering existing font).
- Do not allow mouse-over of invalid glyphs.

- Fix bug that caused the Help button to remain enabled as it was being modified before it was even created.
- Do a better job at finding the correct glyph under the mouse.

- Ensure the active cell is cleared correctly.

- Invalidate the rect around the previously active cell to ensure it gets redrawn as inactive.

- Fix bug from CORE-10518 (initial active cell was not being invalidated on scroll).

- Do not try to copy a character to the output if there is no active cell selected.

- Populate the advanced portion of the screen with several built-in code pages (the list is hardcoded so that we don't enumerate everything).

- Add functionality to filter the character map by a code page (called a character set in this program).

- Some fonts list 0x0000 as drawable, even when it isn't, so ignore any valid glyphs that contain it.