Now it properly fails if libmagic is not installed in the system.
The error message would look like:
```
CMake Error at cmake/modules/FindPackageHandleStandardArgs.cmake:230 (message):
Could NOT find Magic (missing: LIBMAGIC_LIBRARY LIBMAGIC_INCLUDE_DIR)
(Required is at least version "5.39")
Call Stack (most recent call first):
cmake/modules/FindPackageHandleStandardArgs.cmake:600 (_FPHSA_FAILURE_MESSAGE)
cmake/modules/FindMagic.cmake:5 (find_package_handle_standard_args)
cmake/build_helpers.cmake:971 (find_package)
CMakeLists.txt:81 (addBundledLibraries)
```
### Problem description
The current `FindMagic.cmake` module doesn't properly report failure
about absent libmagic libs and #includes. This behavior leads to the
compile errors on the build stage (possibly after some time, which will
be simply wasted). This Find module should set the `Magic_FOUND`
variable and handle all required variables( LIBMAGIC_INCLUDE_DIR and
LIBMAGIC_LIBRARY) to present.
But the current module sets the `libmagic_FOUND` variable, so the CMake
assumes that it is found something. This behaviour should also be
handled by `find_package_handle_standard_args()` ("FPHSA"), and it is
actually handled, but as we requested the `Magic` package to be
required, the former function ("FPHSA") didn't stop the configure
process.
### Implementation description
- Clean up the unused ifs, as "FPHSA" already done it better.
- Use the proper name for "FPHSA" so it could set the proper
`Magic_FOUND` and could make sure that the requested package is
`REQUIRED`.
### Screenshots
Before:
```
-- Could NOT find libmagic (missing: LIBMAGIC_LIBRARY LIBMAGIC_INCLUDE_DIR)
```
<img width="1005" height="24" alt="изображение"
src="https://github.com/user-attachments/assets/082e2842-ff94-4418-8f86-86021c7dd23d"
/>
After:
```
CMake Error at cmake/modules/FindPackageHandleStandardArgs.cmake:230 (message):
Could NOT find Magic (missing: LIBMAGIC_LIBRARY LIBMAGIC_INCLUDE_DIR)
(Required is at least version "5.39")
Call Stack (most recent call first):
cmake/modules/FindPackageHandleStandardArgs.cmake:600 (_FPHSA_FAILURE_MESSAGE)
cmake/modules/FindMagic.cmake:5 (find_package_handle_standard_args)
cmake/build_helpers.cmake:971 (find_package)
CMakeLists.txt:81 (addBundledLibraries)
```
### Additional things
Closes#2244 .
Rationale: The `IMHEX_PLUGINS_IN_SHARE` is a hack to prevent the appimage from loading plugin from system imhex installation, like /usr/lib/imhex/
In reality, I do not think people compile plugins specifically for the AppImage (plugins must be compiled for the specific imhex & compiler version the imhex binary is used), and this lets us remove the hack
Editor was attempting to delete non-existent chars which is UB. Fixed by
checking before deleting. Also fixed was a problem created by having to
press enter to change the search string which advanced the selection to
the first match. In the next step one would expect that pressing enter
on the replace field would replace the selected item but was replacing
the item found after he first.
This was fixed by always replacing the current selection first. If the
replacement is the same as the searched term then replacing won't
advance the cursor, but if they are different then the current match
will no longer exist so it would search fora new one.
