Support multiple options for comment trigger sequences

[davidavetyan]

Is your feature request related to a problem? Please describe.
When working on multiple projects that have different doxygen comment styles, I have to change the trigger sequence and first line settings each time to match the current style.

Describe the solution you'd like
Currently the doxdocgen.c.triggerSequence setting can have only one value. Please change it to accept an array of values, like so:
"doxdocgen.c.triggerSequence": [ "/**", "/*!", "///", "//!" ].
Also please define the default (empty) value of doxdocgen.c.firstLine to mean "match the trigger sequence".

[samkusin]

This would be very useful as I have both C and C++ code in my project, and C++ code often treats the /// prefix for block documentation comments and ///< for single line documentation (while C code often uses the "older" style which is the default for this plugin.)