WPF-947138 : Add additional information about styling and brush customization in DomainUpDown documentation

[SekarSivalingam]

Description

Updated the Appearance and Styling section of the SfDomainUpDown UG documentation.

1. Added details about the UpDownStyle property and its usage.
2. Included an example code snippet demonstrating how to customize the up/down buttons.
3. Documented theme support details for the SfDomainUpDown control.

Task and Ticket

Task: https://dev.azure.com/EssentialStudio/Mobile%20and%20Desktop/_workitems/edit/947138/
Ticket: https://support.syncfusion.com/agent/tickets/702896

[SyncfusionBuild]

Build Status: INQUEUE 🕒
Build Location: WPF-947138-Update_Appearance_Styling_DomainUpDown_hotfix

[SyncfusionBuild]

Build Status: INPROGRESS 🔃
Build Location: WPF-947138-Update_Appearance_Styling_DomainUpDown_hotfix

[SyncfusionBuild]

CI Status: SUCCESS ✅
Source Compilation: SUCCESS ✅
Build Location: WPF-947138-Update_Appearance_Styling_DomainUpDown_hotfix
Image Alt Text Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)
Image Size Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)
Image Name Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)
FT Layout Syntax Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)
Front matter Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)
File Path Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)
CodeSnippet File Path Missing Error(s): 0
Toc Anchor Tags Validation Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)
MD Tag Validation Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)