Proposal: Change default location of ~/.lakectl.yaml

[ozkatz]

Why

lakectl is configured using a yaml file located in $HOME/lakectl.yaml.
While this makes perfect sense for lakectl, it is also currently used by other lakeFS clients such as the high level python SDK - and libraries that depend on it.

This is confusing!

When

Currently I'm only aware of these 2 tools that look for this file. As time passes I'm sure more tools will follow. So soon?

How

In a non-breaking way. Allow both lakectl and the Python SDK to look for a more aptly-named $HOME/.lakefs/client.yaml (happy to hear better suggestions so that we don't end up replacing it yet again in the future) -- and if that doesn't exist, fall back to $HOME/.lakectl.yaml.

• lakectl and SDK should implement fallback logic from new file name to old
• lakectl should create this file by default instead of the old name in lakectl config
• the web UI should recommend downloading the config to the new location post-setup
• lakeFS docs should be adjusted to refer to the new name by deafult
• python SDK docs, (+ possibly docs of dependent tools such as lakefs-spec) should start using new path