Infrastructure: split TLuaInterpreter.cpp's Mudlet Objects files out …

…separately (try 2) (Mudlet#7154)

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#### Brief overview of PR changes/additions
Split TLuaInterpreter.cpp into a domain-specific Mudlet Objects
functions file.
#### Motivation for adding to Mudlet
A 18k line C++ files makes a lot of tools cry.
#### Other info (issues closed, discussion etc)
I've purposefully put the new files into a similar but random-ish
location in mudlet.pro and CMakeLists.txt to reduce the changes of
conflicts when merging the PRs. We can fix the order in a single PR
afterwards.

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Co-authored-by: Vadim Peretokin <[email protected]>

src/CMakeLists.txt

@@ -123,6 +123,7 @@ set(mudlet_SRCS
     TLinkStore.cpp
     TLuaInterpreter.cpp
     TLuaInterpreterNetworking.cpp
+    TLuaInterpreterMudletObjects.cpp
     TLuaInterpreterMapper.cpp
     TMap.cpp
     TMapLabel.cpp