Fix loading app local ICU

[tarekgh]

#57942

.NET runtime is using the ICU library for globalization. We have started using a couple of new APIs (e.g., ubrk_close and ubrk_openRules) that we didn't use before. During runtime we get the pointer to such API dynamically from the ICU library libicui18n which works fine when using whatever installed ICU version on the system. The problem occurs when using app-local version (which the app decides to use ICU version installed from NuGet package). The runtime will not be able to resolve the API against libicui18n because NuGet package libraries export these APIs from different library.
The fix here is to use libicuuc instead of libicui18n which guarantees to have API exports in all environments (system installed ICU or app-local ICU).

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Issue Details

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#57942

.NET runtime is using the ICU library for globalization. We have started using a couple of APIs (e.g., ubrk_close and ubrk_openRules) that we didn't use before. During runtime we get the pointer to such API dynamically from the ICU library libicui18n which works fine when using whatever installed ICU version on the system. The problem occurs when using app-local version (which the app decides to use ICU version installed from NuGet package). The runtime will not be able to resolve the API against libicui18n.
The fix here is to use libicuuc instead of libicui18n which guarantees to have API exports in all environments (system installed ICU or app-local ICU).

Author:	tarekgh
Assignees:	-
Labels:	area-System.Globalization
Milestone:	-

[tarekgh]

CC @martincostello

[tarekgh]

#35930

[tarekgh]

/backport to release/6.0-rc1

[github-actions]

Started backporting to release/6.0-rc1: https://github.com/dotnet/runtime/actions/runs/1161031691