Language: replace "upload" with "import" #817
Description
Current state
References to "upload" are everywhere
Proposed change
Rename labels and variable names from "upload" to "import"
(eg. "import to IPFS", /ipfs-companion-imports/ directory on MFS, etc).
Motivation
"upload to IPFS" brings some confustion, users reuse mental model of the old web suggesting that data is pushed to a third party server, while in truth data is just imported to local node and optionally preloaded to external one.
"import" is a safe alternative: Filecoin uses import term for similar purpose, and ipfs add may be renamed to ipfs import in the future (see ipfs-inactive/interface-js-ipfs-core#552).