Support new N++ plugin command NPPM_GETTABCOLORID

[alankilborn]

A new notepad member function is needed to support a plugin command new to (presumably) N++ release 8.6.8: NPPM_GETTABCOLORID

The new function should (ideally?) be callable as color_id = notepad.getTabColorID(view, tabIndex) where view and tabIndex are both default arguments with value -1 (to mean active/current view and active/current tabIndex).

Details on the N++ implementation:

• https://github.com/notepad-plus-plus/notepad-plus-plus/commit/9244cd09430c82ecff805ea862c9133d5cb56ded
• https://github.com/notepad-plus-plus/npp-usermanual/issues/671

Other related:

• https://github.com/notepad-plus-plus/notepad-plus-plus/pull/15142
• https://github.com/notepad-plus-plus/notepad-plus-plus/issues/15115

[chcg]

I will wait until release of 8.6.8 before I update pythonscript.