Feature: Add --this flag in axii edit module-definition

Support --this flag in axii edit module-definition as an alternative to the module_name argument.

Usage example:

[▽ code] rkartmann@i61nb092:~/code/armarx/ArmarXCore/build$ axii edit module-definition --this
Requested to edit module explaining the path '/home/rkartmann/code/armarx/ArmarXCore/build'. This requires an active workspace.
Loaded workspace 'code' at '/home/rkartmann/code'.
Found module 'armarx/ArmarXCore'
Edit module definition file '/home/rkartmann/axii/data/modules/armarx/ArmarXCore.json' ...
# (editing the file)
Save module definition at '/home/rkartmann/axii/data/modules/armarx/ArmarXCore.json' ...

Other argument/option combinations:

[▽ code] rkartmann@i61nb092:~/code/armarx/ArmarXCore/build$ axii edit module-definition
Error:  Missing argument/option: specify either 'module_name' or '--this'.
[▽ code] rkartmann@i61nb092:~/code/armarx/ArmarXCore/build$ axii edit module-definition armarx/ArmarXGui --this
Error:  You may specify either 'module_name' or '--this', but not both.
[▽ code] rkartmann@i61nb092:~/code/armarx/ArmarXCore/build$ axii edit module-definition armarx/ArmarXCore 
Edit module definition file '/home/rkartmann/axii/data/modules/armarx/ArmarXCore.json' ...
Save module definition at '/home/rkartmann/axii/data/modules/armarx/ArmarXCore.json' ...