Encoding issue with textual export/import

[stephanelacrampe]

I am not sure to what extent this is linked to #770 and #650 and eclipse-sirius/sirius-web#3889 but the textual import/export is not working correctly with SysON when using Japanese characters.

Problem with importing:

• I have a textual sysml file with the following text: package 'おはよう'; - Importing this file in SysON produces a package with a name '????'

Problem with exporting:

• I have a sysml project with a single package in it with 'おはよう' for its name. Exporting it to a textual sysml file produces ???? in the package name

Problem with the function "New Objects From Text"

• Typing package 'おはよう'; in this box do create a package in the model but with ???? in its name