Add retries, repeated runs, and flaky-test reporting

tests/fixtures/zig-test.jsonmodified+4-1

Changes to tests/fixtures/zig-test.json

		⋯2 linesShow the 2 lines above this hunk@@ -3,7 +3,10 @@
3	3	"test_dir": "tests/fixtures",
4	4	"pattern": "filter_fixture.zig",
5	5	"recursive": false,
6		- "filter": "selected test passes"
	6	+ "filter": "selected test passes",
	7	+ "retries": 1,
	8	+ "repeat": 2,
	9	+ "fail_on_flaky": false
7	10	},
8	11	"sharding": {
9	12	"index": 1,