ci : add model tests + script wrapper (#4586)

* scripts : add lib.sh and lib_test.sh

* scripts : stub out new ci-run.sh script

* scripts : switch to PascalCase for functions

This looks a little odd at first, but I find it very useful as a
convention to know if a command is part of our code vs a builtin.

* scripts : add some fancy conversion from snake_case to PascalCase

* Add venv to ci/run.sh

* Revert scripts work

* scripts : add wrapper script for local use of ci/run.sh

* Simplify .gitignore for tests, clang-tidy fixes

* Label all ctest tests

* ci : ctest uses -L main

* Attempt at writing ctest_with_model

* Update test-model-load-cancel

* ci : add ctest_with_model for debug and release

ggml-ci

* Fix gg_get_model function

ggml-ci

* got stuck on CMake

* Add get_model.cpp to tests/CMakeLists.txt

ggml-ci

* Fix README.md output for ctest_with_model

ggml-ci

* workflows : use `-L main` for all ctest

ggml-ci

* Fixes

* GG_RUN_CTEST_MODELFILE => LLAMACPP_TESTMODELFILE
* Always show warning rather than failing if model file variable is not
  set

* scripts : update usage text for ci-run.sh

tests/get-model.cpp

@@ -0,0 +1,21 @@
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+#include "get-model.h"
+
+char * get_model_or_exit(int argc, char *argv[]) {
+    char * model_path;
+    if (argc > 1) {
+        model_path = argv[1];
+
+    } else {
+        model_path = getenv("LLAMACPP_TEST_MODELFILE");
+        if (!model_path || strlen(model_path) == 0) {
+            fprintf(stderr, "\033[33mWARNING: No model file provided. Skipping this test. Set LLAMACPP_TEST_MODELFILE=<gguf_model_path> to silence this warning and run this test.\n\033[0m");
+            exit(EXIT_SUCCESS);
+        }
+    }
+
+    return model_path;
+}