Add Alpine Linux build

[ronaldtse]

Add Alpine Linux build, fixes #27

[ronaldtse]

GitHub Actions is down at the moment, will re-check tomorrow.

[ronaldtse]

There is also this error in the Ubuntu build:

CMake Error at CMakeLists.txt:254 (include):
[28](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:28)
  include could not find requested file:
[29](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:29)

[30](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:30)
    CodeCoverage
[31](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:31)

[32](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:32)

[33](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:33)
CMake Error at CMakeLists.txt:255 (setup_target_for_coverage):
[34](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:34)
  Unknown CMake command "setup_target_for_coverage".

[maxirmx]

There is also this error in the Ubuntu build:

CMake Error at CMakeLists.txt:254 (include):
[28](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:28)
  include could not find requested file:
[29](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:29)

[30](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:30)
    CodeCoverage
[31](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:31)

[32](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:32)

[33](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:33)
CMake Error at CMakeLists.txt:255 (setup_target_for_coverage):
[34](https://github.com/metanorma/libemf2svg/runs/5649202688?check_suite_focus=true#step:5:34)
  Unknown CMake command "setup_target_for_coverage".

It requires set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_CURRENT_SOURCE_DIR}/cmake/")otherwise CodeCoverage function is not defined

[maxirmx]

@ronaldtse I fixed build script but there is segfault with one of the tests on alpine

[ronaldtse]

Thanks @maxirmx ! Can you help further find out where that segfault is due to?

[maxirmx]

The test against Arabic/Hebrew charset fails. It may take some time to understand specifics of bidi (Unicode Bidirectional) implementation in Alpine Linux