Blob endpoint fails to store Excel/Fails to determine encoding

[krowvin]

When working on storing an excel file:

i.e.
https://cwms-data.usace.army.mil/cwms-data/blobs/24HOURDATA.XLSX?office=SWT

I was running into an issue where if I attempted to store raw bytes and have it encode this it would fail to determine the encoding.
I.e.

• cwms-python/cwms/catalog/blobs.py

  Line 93 in c930742

  if "value" in data and not is_base64(data["value"]):

Attempts to check if it is already base64 encoded for backwards compat

then this part encodes it for a comparison

• cwms-python/cwms/utils/checks.py

  Lines 7 to 8 in c930742

  	decoded = base64.b64decode(s, validate=True)
  	return base64.b64encode(decoded).decode("utf-8") == s

But if you encode something that is not encoded already it will result in a failed check.

I'm not sure how to better check the encoding

But perhaps at a minimum we could check if bytes vs string are sent in:
I.e.

    value = data["value"]
    if isinstance(value, bytes):
        data["value"] = base64.b64encode(value).decode("utf-8")
    elif isinstance(value, str):
        data["value"] = base64.b64encode(value.encode("utf-8")).decode("utf-8")
    else:
        raise TypeError("Blob 'value' must be bytes or string")

then within the string check to see if it's already a base64 encoded string (perhaps we can do this with headers instead of attempting a re-encode?)

Wanted to discuss options before I submitted a PR to fix!