Closes #40906
Closes #39729

SFTP uploads weren't quoting the install directory which was causing
extension syncing to fail. We were also only running `install_extension`
once per remote-connection instead of once per project (thx @feeiyu for
pointing this out) so extension weren't being loaded in subsequently
opened remote projects.

Release Notes:

- N/A

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Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>