[Eclipse] Use a command instead of a direct call to save a file

[wgalanciak]

Is your feature request related to a problem? Please describe.
There are some plugins (e.g. https://github.com/wangzw/CppStyle) that override a default save action in Eclipse in order to perform some additional pre or post save operations. They are not compatible with CodeTogether because currently, it uses Workbench API to trigger save.

Describe the solution you'd like
The goal of this task is to investigate if we can switch to command execution for save action. As a result, regular on save actions as well as some custom plugins (like mentioned CppStype one) would work fine.