Use os.stat to get the size instead of reading the file in memory

[sanathkumarbs]

Here the entire file is read, that's a very expensive operation and can easily hit a MemoryError.

https://github.com/F5Networks/f5-common-python/blob/0a16f6e10b29ba3bca1f1dabf9a6f8f5b438296c/f5/bigip/mixins.py#L272 To get the size, it might be better off to do:

import os
def _upload(self, fileinterface, **kwargs):
        size = os.stat(fileinterface.name).st_size

Wanted to bounce this idea before I created a PR. Let me know if this fix makes sense, will create a PR for this.

[caphrim007]

@sanathkumarbs so long as it meets two requirements

1. does it return the same value
2. is it more performant (faster, less memory, etc)

if the above are true, send the PR.

[wojtek0806]

@sanathkumarbs do you still need this if so can you send a PR ?