Add session language filter.

[babogoos]

• Use distinct session language to filter out sessions.
• The Lang filter filed would not show if all session language is null.

[fdff87554]

@babogoos @coin3x 我這邊有看過一遍了，方便麻煩你再幫忙看看嗎？沒問題我想說是不是可以 merge 了？