GUACAMOLE-925: Add Russian keymap support "ru-ru-qwerty"

[VAGurko]

The keymap "ru_ru_qwerty.keymap" has been added to the "src/protocols/rdp/Makefile.am" file to support the Russian keyboard layout.
The file "src/protocols/rdp/keymaps/ru_ru_qwerty.keymap" has been added to support the Russian keyboard layout.

[mike-jumper]

This (and other lines) duplicates the same scancodes and modifier combination as a previous line:

map +caps +shift 0x10..0x1B 0x2B ~ "qwertyuiop{}|"

There needs to be something that distinguishes the context of typing these characters for the mapping to work correctly. For example, if the user presses "q" or "й", this map will result in the same sequence of scancodes being sent, but that sequence will not necessarily be interpreted to produce "q" (or "й"). Proper behavior will depend on some sort of additional state that Guacamole isn't aware of, and the intent of the user may not match what ultimately ends up typed.

Is there something else that needs to be supported by these keymaps for this to be unambiguous? Does the Russian keyboard have additional modifier keys or state that needs to be represented?