Tracking issue for filesystem support

[hairyhenderson]

This issue tracks the various filesystems I want to be supported by this module, and their current state.

• ✔️ = Support planned/complete
• ✖️ = Not supported/will not be supported
• empty = Unknown/undecided/incomplete

FS	Context?	Headers?	MIME?	Done?
AWS SM	✔️			✔️
AWS SMP	✔️			✔️
Azure Blob	✔️		✔️	✔️
Consul	✔️	✔️	✔️	✔️
File	✖️	✖️	✖️	✔️
Git	✔️		✖️	✔️
GCS	✔️		✔️	✔️
HTTP	✔️	✔️	✔️	✔️
S3	✔️		✔️	✔️
Vault	✔️	✔️	✔️	✔️

• FS: Filesystem (may include multiple types of support, e.g. git with file/http/ssh/daemon)
• Context: Whether or not injecting a context.Context makes sense (i.e. cancellation will be able to be supported)
• Headers: Whether or not injecting HTTP headers makes sense
• MIME: Whether or not MIME Content-Type detection will work (extension-based guessing used otherwise)
• Done: Whether or not basic support is implemented

[hairyhenderson]

With #93 and #86 finished, this can now be closed. I've got all the filesystem support that I've initially planned on now!