kvssink CI enhancements!

[sirknightj]

Issue #, if available:
#1225

Description of changes:

1. Fixing the unit tests with kvssink.

Unit tests were reported broken in the issue above. Due to a combination of two combined issues:

1. Implicit bad gchar* (aka char*) -> std::string conversions. If a nullptr is passed into the std::string constructor, a segfault will occur.
2. Missing pads in the unit tests

In KVS client & stream initialization, the kvssink->content_type (gchar*) field is obtained from the element directly to the left (pad). However, in the unit tests, the pad was not constructed or attached. As such, that kvssink->content_type is a nullptr. When it gets passed into the StreamDefinition constructor, it gets implicitly cast into the std::string.

Note that the null inputs case is only possible through programatic use of GStreamer and kvssink. When using gst-launch-1.0 or gst_parse_launch(), properties can't be set to null, since the kvssink properties are configured with default values. Hence, this effort will assist developers using kvssink programatically.

To fix this:

1. The pads were constructed and linked in the unit tests.
2. Added null checks to the C- char* strings before converting them to C++ strings.
3. Added new unit tests to check that kvssink exits gracefully if the gchar* fields are nullptrs.

2. Adding a github action to build and run the unit tests

2.1. Adding a session token parameter to the unit tests

• Since we need to use temporary credentials, the gstreamer unit tests now have the session token logic added.

2.2. Running the repaired gstreamer tests automatically for every pull request

• Using the docker images from the AWS ECR gallery to avoid random github actions runner updates from breaking the builds.

Testing:

• Ran it on my local setup to check that the tests pass. Tried both with session token and without.
• The new error messages show up as part of the GStreamer logs. Run GST_DEBUG=4 ./tst/gstkvsplugintest.

0:00:00.035717708 33125 0x600000e8c5d0 WARN                 kvssink gstkvssink.cpp:1672:gst_kvs_sink_change_state:<kvssink> error: Failed to init kvs producer. Error: Assertion failed: kvssink->stream_name is unexpectedly NULL!

0:00:00.031656167 25576 0x600000f5c960 WARN                 kvssink gstkvssink.cpp:1672:gst_kvs_sink_change_state:<kvssink> error: Failed to init kvs producer. Error: Assertion failed: kvssink->content_type is unexpectedly NULL!

3. Verifying the debug dump dir and kvssink on different flavors (Windows, mac, linux).

• Run kvssink with videotestsrc for 15 seconds with the KVS_DEBUG_DUMP_DATA_FILE_DIR set. Then, run mkvinfo on the output MKV file to verify that it's generated.

Note

The valgrind checks currently work but have been commented out as they are failing. Fixing the memory leak in the kvssink unit tests can come as part of a future development.

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