Revert "skip profile-scan if CSN-only"

Launch time improvement was only very minor, and caused modified profiles not to be loaded.

Show settings before profile-scan is complete

The old combobox code let the settings get displayed early but the combobox change had stopped that

Reduced launch time, set combobox datasource, skip profile-scan if CS…

…N-only

For fastest launch enable the "Show from CustomSettingNames.xml only" button and close/relaunch.

Update Forced Preset Letter to the new auto-preset selection

App: switch to .NET 4.8

4.8 is included in Win10+ while 4.8.1 needed redist installed on some.

Settings: show DLSS override version in dropdown/description, and

remove unused mark from DLSS-RR preset E.

Tries to parse nvngx_config.txt and find the latest override version,
displays it in dropdown.

Needs testing with systems that have modified nvngx_config (eg. through
updating DLSS override with tools), may release test version for it
soon.

UserSettings: fix exception when settings.xml doesn't exist

Form: allow searching for profile by EXE name when Enter is pressed

If entered text isn't found as a profile-name, it'll now be searched as
an EXE filename/filepath

eg. can type mpc-hc64.exe and press Enter to open the Media Player
Classic profile.

Form: allow ESC key to clear search filter

Form: handle filtering inside `RefreshCurrentProfile`, handle backspace

Fixes momentary flicker when saving profile, also seemed to help with
the collapsible groups perf issue, so removed the 250ms wait before
applying filter

Updated with NVDRS_APPLICATION_V4 from nvapi r575