More robust `is_supported_format` suffix check

[function2-llx]

Is your feature request related to a problem? Please describe.
Sometimes the data I receive have uppercase suffixes (e.g., IMAGE.PNG), this could be recognized as the lowercase counterpart.

Describe the solution you'd like
Simply change this line

MONAI/monai/data/utils.py

Line 1103 in 025c107

if len(tokens) == 0 or all("." + s.lower() not in "".join(tokens) for s in suffixes):

to something like

    if len(tokens) == 0 or all("." + s.lower() not in "".join(map(str.lower, tokens)) for s in suffixes):

If this is acceptable, I'm happy to open a PR.

[wyli]

Thanks, a PR would be great!