Description

This PR modifies the CMake build configuration to improve jpegli integration for mobile (iOS/Android) and web (Emscripten) platforms.

Changes:

• Restructured CMake targets to expose object libraries for easier static linking
• Enabled cross-platform usage of jpegli as a fully static library
• Maintained compatibility as a drop-in replacement for libjpeg

Usage Example:

Projects can now integrate jpegli by including the object libraries in their build:

list(APPEND SOURCES
  $<TARGET_OBJECTS:brotlicommon>
  $<TARGET_OBJECTS:brotlidec>
  $<TARGET_OBJECTS:brotlienc>
  $<TARGET_OBJECTS:hwy>
  $<TARGET_OBJECTS:jxl_dec-obj>
  $<TARGET_OBJECTS:jxl_enc-obj>
  $<TARGET_OBJECTS:jxl_cms>
  $<TARGET_OBJECTS:jpegli-static-obj>
  $<TARGET_OBJECTS:jpegli-libjpeg-obj>
)

This allows seamless integration across platforms while maintaining the ability to use jpegli as a libjpeg replacement.

Pull Request Checklist

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