CMake: add lib skeleton and google-tests

pasada-lib/CMakeLists.txt

@@ -0,0 +1,24 @@
+project(Pasada_Lib)
+
+SET(PASADA_SRC
+        library.cpp
+)
+
+if(PASADA_BUILD_TESTS)
+    # must build a STATIC library for google-tests to successfully consume us
+    # (otherwise, strange runtime errors ensue when trying to call into the lib)
+    add_library(pasada STATIC
+            ${PASADA_SRC}
+    )
+else()
+    add_library(pasada SHARED
+            ${PASADA_SRC}
+    )
+endif()
+
+target_include_directories(pasada
+        PUBLIC
+        ${CMAKE_CURRENT_SOURCE_DIR}/include
+)
+
+set(CMAKE_CXX_STANDARD 20)