feat(Upload): redesign upload components

[ArgoZhang]

Link issues

fixes #5981

Summary By Copilot

Regression?

• Yes
• No

Risk

• High
• Medium
• Low

Verification

• Manual (required)
• Automated

Packaging changes reviewed?

• Yes
• No
• N/A

☑️ Self Check before Merge

⚠️ Please check all items below before review. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• Merge the latest code from the main branch

Summary by Sourcery

Redesign all upload components on a unified base to streamline multi-file and directory uploads, progress and lifecycle callbacks, default file presets, and customizable file icons, while cleaning up obsolete APIs, improving styling, and updating demos and CI configuration.

New Features:

• Support uploading entire directories via a new IsDirectory parameter
• Enable multi-file uploads with IsMultiple and MaxFileCount, deprecating IsSingle/Max
• Allow preset file lists through DefaultFileList and a global OnAllFileUploaded callback
• Optionally show upload progress per file with ShowProgress and progress update callbacks
• Expose download and cancel operations per file via OnDownload, OnCancel, and ShowDownloadButton
• Add custom file format icon support via OnGetFileFormat
• Extend InputUpload, ButtonUpload, AvatarUpload, CardUpload, and DropUpload to use a unified UploadBase with new capabilities

Enhancements:

• Refactor all upload components to inherit from a single UploadBase, removing duplicate base classes
• Deprecate old IsSingle/Max parameters in favor of IsMultiple/MaxFileCount
• Reorganize CSS/SCSS variables and class builders for consistent styling and layout
• Improve UploadFile extensions to detect image formats, base64 URLs, and allowed extensions
• Clean up obsolete code and consolidate parameter handling across ButtonUpload, AvatarUpload, CardUpload, InputUpload, and DropUpload
• Update sample/demo pages and menu entries to showcase redesigned upload components

CI:

• Fix test project name in build workflow from UnitTestLocalization to UnitTest.Localization

[codecov]

Codecov Report

Attention: Patch coverage is 99.53596% with 2 lines in your changes missing coverage. Please review.

Project coverage is 99.99%. Comparing base (4ad4ea4) to head (01ce5c9).

Files with missing lines	Patch %	Lines
...trapBlazor/Components/Upload/AvatarUpload.razor.cs	97.43%	0 Missing and 1 partial ⚠️
...lazor/Components/Upload/UploadPreviewList.razor.cs	98.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##              main    #6049      +/-   ##
===========================================
- Coverage   100.00%   99.99%   -0.01%     
===========================================
  Files          703      704       +1     
  Lines        31019    30979      -40     
  Branches      4386     4380       -6     
===========================================
- Hits         31019    30977      -42     
- Partials         0        2       +2     

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