* feat(plugin): Add filestore Windows implementation
* Define UA_DT_REG and UA_DT_DIR
* Remove build flag and use __linux__ or UA_ARCHITECTURE_WIN32 in places which used to check only for __linux__
* feat(plugin): Add filestore backend security policies to support writing updated certificates back to the file system
* feat(tests): Add test cases for the filestore security policies and the updateCertificate function
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Co-authored-by: Julius Pfrommer <jpfr@users.noreply.github.com>