refactor: update RimeWithWeasel.cpp, style holded by session

[fxliang]

• fix: style incorrect in some case when dark mode switches. introduced by color_scheme_dark for Windows 10 1809+ #1046, fix color_scheme_dark 配置不能立即生效 #1066
• refactor: show_notifications_when feat: add option shown_notifications_when: {string}, to determine when to show notifications #1031, keyword is changed to show_notifications, bool type or list of { option_name in schema / keyword 'schema'}. it can be set up in both weasel.yaml(weasel.custom.yaml) and schema file.
• feat: notifications tips for customized switches
• feat: global ascii mode, with param global_ascii: {bool}
• feat: show_notifications_time customizable with param show_notifications_time: {int}, unit: ms
• chore: UI function de-warning.

# configuration: when to show notifications
show_notifications:  true    # default true to enable all tips, false to disable all tips (except deployment's)
# list type of setting
#show_notifications:
#  - ascii_mode 
#  - ascii_punct
#  - full_shape
#  - simplification
#  - customized_option_name_in_schema
#  - schema    # this is for tip after schema switched

# how long a period notifications shows
show_notifications_time: 1200
# use global ascii status, set true means all session in the same ascii mode all the time.
global_ascii: false

dark mode scheme auto switching, with schema specified color scheme and dark color scheme.