Description of the Issue

Notepad++ currently provides the NPPM_CREATESCINTILLAHANDLE call for plugins to create Scintilla instances to be used in plugins. However with the move to Scintilla v5+, a plugin can no longer use SCI_SETLEXER since this has been removed by Scintilla.

Notepad++ needs a new API call so that Notepad++ can call Lexilla's CreateLexer() function and return the pointer to the ILexer object it to the plugin.

Steps to Reproduce the Issue

1. A plugin creates a new Scintilla handle using NPPM_CREATESCINTILLAHANDLE
2. Call SCI_SETLEXER on the Scintilla handle
3. Nothing happens since Scintilla ignores this message

Debug Information

Notepad++ v8.4.2   (64-bit)
Build time : May 29 2022 - 16:47:30
Path : C:\Program Files\Notepad++\notepad++.exe
Command Line : $COMMAND_LINE_PLACEHOLDER$
Admin mode : OFF
Local Conf mode : OFF
Cloud Config : OFF
OS Name : Windows 10 Home (64-bit) 
OS Version : 21H2
OS Build : 19044.1706
Current ANSI codepage : 1252
Plugins : 
    BetterMultiSelection (1.5)
    ElasticTabstops (1.4)
    ezLCDLua (1.1)
    LuaScript (0.12)
    mimeTools (2.8)
    NppConverter (4.4)
    NppExport (0.4)
    NppMenuSearch (0.9.3)