Change default file format to 1.8 across various tests and examples, updating file creation and access logic accordingly.
Behavior:
Default file format version changed to 1.8 in H5Pfapl.c.
Updated file creation and access to use 1.8 format in h5ex_g_compact.c and test_file_image.c.
Set earliest file format in multiple test files including cache_tagging.c, dtypes.c, and links.c.
Tests:
Modified expected output in tools/test/misc/expected/*.ls files to reflect new file format locations.
Adjusted test logic in test_file_image.c and cache_tagging.c to accommodate format changes.
Misc:
Added comments and TODOs for future format testing in test_file_image.c.
Minor variable renaming for clarity in test_file_image.c.
Added text to the usage of h5clear to explain that this tool is not
for fixing corrupted files but simply for helping in the inspection
of the damage..
Fixed expected output for testing the modified usage.