tesseract: fix imported target / system libs / interface definition

[SpaceIm]

Specify library name and version: lib/1.0

• I've read the guidelines for contributing.
• I've followed the PEP8 style guides for Python code in the recipes.
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• I've tried at least one configuration locally with the
  conan-center hook activated.

Also, if not already fixed, this new revision closes #4848

[SpaceIm]

You can deduce official imported target from this line (no NAMESPACE property during export): https://github.com/tesseract-ocr/tesseract/blob/75103040c94ffd7fe5e4e3dfce0a7e67a8420849/CMakeLists.txt#L542
And also the fact that the exported target is libtesseract + EXPORT_NAME property is not explicitly set.

TESS_IMPORTS interface definition if shared:
https://github.com/tesseract-ocr/tesseract/blob/75103040c94ffd7fe5e4e3dfce0a7e67a8420849/CMakeLists.txt#L461-L464

[SpaceIm]

with_training=True is probably broken. When True, icu, pango, cairo and fontconfig should be required, USE_SYSTEM_ICU set to True during CMake configuration, and bin folder added into PATH.

Oh yes I see, there is warning about this option. Let's fix it in another PR.

[conan-center-bot]

All green in build 1 (4f6edcc0cebd7a460254cf3864106691dff39e4f):

• tesseract/4.1.1@:
  All packages built successfully! (All logs)

[SpaceIm]

Tesseract::libtesseract should become the new imported target in 5.0.0. Therefore this recipe provides now both imported targets: libtesseract and Tesseract::libtesseract (instead of only Tesseract::libtesseract before this PR).

[conan-center-bot]

All green in build 5 (770d232151108426f4fadf48e2967434865c96a0):

• tesseract/4.1.1@:
  All packages built successfully! (All logs)