Summary: Mos.Olimpiada adds Arab language competition

Why It Matters: This change adds a new subject to the competition.

What Changed:

• A new competition for "Арабский язык" (Arabic language) for grades 7-11 was added, with dates for the qualifying round.
• The "Робототехника" (Robotics) competition now shows dates for its qualifying rounds.
• The "Физика" (Physics) competition now shows dates for its qualifying rounds.
• The "Химия" (Chemistry) competition now shows dates for its qualifying rounds.
• The "Экология" (Ecology) competition now shows dates for its qualifying rounds.
• Some empty links were removed or changed.