WIP: Add Range Band Support UG Content for Spark Chart in .NET MAUI Toolkit

[Vallarasu4653]

Description

This PR introduces Range Band support UG content for the Spark Chart control in .NET MAUI Toolkit.
Range bands allow highlighting specific value ranges in the chart background, useful for thresholds and performance zones.

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Build Status: INPROGRESS 🔃
Build Location: add_sparkchart_rangeband_content

[SyncfusionBuild]

CI Status: SUCCESS ✅
Source Compilation: SUCCESS ✅
Build Location: add_sparkchart_rangeband_content
Technical Error(s): 0
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CodeSnippet File Path Missing Error(s): 0
Toc Anchor Tags Validation Error(s): 0
MD Tag Validation Error(s): 0

[SyncfusionBuild]

Build Status: INPROGRESS 🔃
Build Location: add_sparkchart_rangeband_content

[SyncfusionBuild]

CI Status: SUCCESS ✅
Source Compilation: SUCCESS ✅
Build Location: add_sparkchart_rangeband_content
Technical Error(s): 0
Spelling Error(s): 0
Image Alt Text Error(s): 0
Image Size Error(s): 0
Image Name Error(s): 0
Front matter Error(s): 0
File Path Error(s): 0
CodeSnippet File Path Missing Error(s): 0
Toc Anchor Tags Validation Error(s): 0
MD Tag Validation Error(s): 0

[SyncfusionBuild]

Build Status: INQUEUE 🕒
Build Location: add_sparkchart_rangeband_content

[SyncfusionBuild]

Build Status: INPROGRESS 🔃
Build Location: add_sparkchart_rangeband_content

[SyncfusionBuild]

CI Status: SUCCESS ✅
Source Compilation: SUCCESS ✅
Build Location: add_sparkchart_rangeband_content
Technical Error(s): 0
Spelling Error(s): 0
Image Alt Text Error(s): 0
Image Size Error(s): 0
Image Name Error(s): 0
Front matter Error(s): 0
File Path Error(s): 0
CodeSnippet File Path Missing Error(s): 0
Toc Anchor Tags Validation Error(s): 0
MD Tag Validation Error(s): 0

[SyncfusionBuild]

Build Status: INPROGRESS 🔃
Build Location: add_sparkchart_rangeband_content

[SyncfusionBuild]

CI Status: SUCCESS ✅
Source Compilation: SUCCESS ✅
Build Location: add_sparkchart_rangeband_content
Technical Error(s): 0
Spelling Error(s): 0
Image Alt Text Error(s): 0
Image Size Error(s): 0
Image Name Error(s): 0
Front matter Error(s): 0
File Path Error(s): 0
CodeSnippet File Path Missing Error(s): 0
Toc Anchor Tags Validation Error(s): 0
MD Tag Validation Error(s): 0

[PreethikaSelvam]

Fine.