refactor: theme checks accross application replaced with central Theme

[SGI-CAPP-AT2]

Description

The theme was being managed by checks at each elements local scope to avoid those redundant checks This PR has refactored it with ThemeExtensions with ThemeData for dark theme and light theme
These color schemes can be accessed through Theme.of(context).extensions<TaskwarriorThemeColors>().

For future color related changes:
Custom Colors to be added inside TaskwarriorThemeColors class with common attribute for light and dark.
After doing such changes also add colors for corresponding attribute specific to Dark Theme and Light Theme inside TaskwarriorColors class.

Also fixed following problems:

1. Search bar bg and color was having white n black color irrespective of theme
2. Constant color scheme was not being used for DatePicker and TimePicker ( refer Date Picker appearing in white even in dark mode, when editing due date in edit task. #411 )
3. Color of tags in filter drawer was BnW scheme irrespective of theme

Fixes #400

closes: #400
closes: #411

Currently Across application there are multiple theme checks being done for every widget build.
Replace issue_no with the issue number which is fixed in this PR

Screenshots

Checklist

• Tests have been added or updated to cover the changes
• Documentation has been updated to reflect the changes
• Code follows the established coding style guidelines
• All tests are passing

[SGI-CAPP-AT2]

@BrawlerXull PR is ready to review, let me know if you find any flaw

[BrawlerXull]

Good one @SGI-CAPP-AT2 I'll test it locally and let you know

[BrawlerXull]

Yet there are many instances where old logic is used please refactor it too

[SGI-CAPP-AT2]

@BrawlerXull , Yes I think We'll need extension to ThemeDatas,
Let me do that changes.
Once done I'll mention you.
Thanks for pointing out

[SGI-CAPP-AT2]

@BrawlerXull , Now you can review and test
I refactored all of the checks with ThemeExtensions.

[linuxcaffe]

Will this change also apply to the widget?? ( see #415 )

[SGI-CAPP-AT2]

Hey @linuxcaffe ,
I think no.
Since widgets are handled with native framework we must find some workaround to apply themes on widget.

[Pavel401]

https://developer.android.com/develop/ui/views/appwidgets/enhance

[SGI-CAPP-AT2]

@Pavel401 Thanks for sharing,
Let me try that as well

[SGI-CAPP-AT2]

Update: Some of Unexpected changes are fixed now, This PR is ready to test and merge

[Pavel401]

>

1. **Update the button colors to align with the design specifications.
2. Correct the onselect theme for the AM/PM indicator.
3. Fix the snackbar appearing completely white in dark mode on the task details page.
4. Perform thorough testing of all UI components in both dark and light modes to ensure consistency.**

[Pavel401]

Keep the old floating button theme

[SGI-CAPP-AT2]

Hey thanks for testing,
I will fix all issues and will check If there are any areas where issues exists.

[Pavel401]

@SGI-CAPP-AT2 Can you also fix the calendar theme in the task details page , right now in the dark mode it shows the light theme of the calendar.

[SGI-CAPP-AT2]

@SGI-CAPP-AT2 Can you also fix the calendar theme in the task details page , right now in the dark mode it shows the light theme of the calendar.

Oh I was using same color scheme for all of the pickers, so I thought it's fixed

Let me do that as well

[SGI-CAPP-AT2]

update: fixes made as per #402 (comment)
also tested all use cases of application known to me