Co-authored-by: Dentomologist <dentomologist@gmail.com>

PRs https://github.com/dolphin-emu/dolphin/pull/13786 and
https://github.com/dolphin-emu/dolphin/pull/13797 had incompatible
changes that resulted in the build being broken when they were both
merged.

Add option to hide them.
Add box to search.
Add ability to edit data symbols and notes in MemoryViewWidget.

Fix a copy-paste error causing MemoryWidget's splitter to load the wrong
state data when creating the MemoryWidget.

For me this caused the side panel to be scrunched up every time I
started Dolphin, but the exact effects probably depend on the state of
your MemoryWidget and CodeWidget.

Fix the input string failing to validate when the "Hex Byte
String" input type is selected and either the user adds a 0x prefix or
the "Hex" box is checked (or both).

The latter failure was particularly troublesome because when "Hex Byte
String" is selected the "Hex" checkbox is disabled. Users would have to
switch to a data type that enabled the box, toggle it, then switch back
to "Hex Byte String" to fix it.

Fix these errors by not adding a prefix when the "Hex" box is checked,
and removing the "0x" prefix from the user's input if present.

Fix validation failing when the user has checked the Hex box and also
includes a "0x" or "-0x" prefix in their input.

Previously an extra "0x" would be inserted, causing the user's input of
"0x13" to become "0x0x13" which would then fail to validate.