2825-P,Q-Dark mode implementation

Description

Implement Dark mode for Tasks app, which will be switched with device's dark-mode status.

• Add & Update dark-mode style
• Add dark-mode colors
• Fix mismatched colors

Issue(s)

• e/backlog#2825 (closed)

Test procedures

Test environment

1. Build OS with FEATURE_BRANCH=Issue-2977_Q
2. Pull the branch & build debug apk using android-studio.
3. Install the apk into device & run.
4. Switch the device to dark-mode.

Steps

Action	Expected result
Navigate through app	All components should be in dark-mode color
Switch device to light-mode	All components should be in light-mode color

Expected result

App will react on device's dark-mode status change

Technical details

- update .gitignore file & hard removed .idea directory from tracking by git

Screenshots

Month view	Week View	Day View

Check list

• Self review
• Test procedure explained
• Tested on fresh install
• Tested applied as an update
• License
• Internal documentation
• User documentation