FreeType: improve library dependency handling, add example

[igrr]

• Updated Zlib library to be compatible with CMake FindPackage module. Now, third party libraries which call find_package(ZLIB) will find espressif/zlib component automatically, provided that it has been added as a dependency into the project.
  • We should do the same in other common components, as well.
• Updated freetype component to have a dependency on zlib
• Configured freetype to not look for Brotli, Harfbuzz, BZ2, libpng libraries. Enabled searching for zlib, which should now find the espressif/zlib component.
• Added a simple example to freetype component to validate its operation.

[igrr]

@fhrbata May I ask you to take a look at this MR, especially the part in e90d4a7bd6780487a737b8dbabd7937074d03756? If you think this is a good idea, I'll add find_package support for other common-enough libraries, like libpng.

[igrr]

@espressif2022 PTAL as well

[igrr]

cc @espzav

[igrr]

@espressif2022 @suda-morris Could you please help review?

[igrr]

Thanks for the review @espzav!