Fix TMPDIR usage

[grumpygreenguy]

Context

Addressing the temp directory issues reported by @AlseinX.
Our scripts have been overloading the system variable TMPDIR; this had worked until now, but it's clashing with pnpm since the latter relies on os.tmpdir() working properly.

Fix

• Use a specific name for the variable that designates the installation directory.
  • Drive-by: make sure the directory is actually set (i.e. no defaults)
• In the few cases where TMPDIR is actually intended to be the catch-all temporary location, set up its creation and cleanup

TODO

• Make sure CI passes (some steps may fail if they're relying on the default value rather than setting the variable)

[0xverin]

I tried it locally, and it works:

Setting up worker in tmp/w-0
Copying files from bin
Copying source files to working directory
bin/key.txt does not exist, this is fine, but you can't perform remote attestation with this.
bin/spid.txt does not exist, this is fine, but you can't perform remote attestation with this.
Initialized worker.
Starting worker 0 in background
worker command is: ['./litentry-worker', '--clean-reset', '-P', '2000', '-w', '2001', '-r', '3443', '-h', '4545', '--running-mode', 'mock', '--enable-mock-server', '--parentchain-start-block', '0', '--enable-metrics', 'run', '--skip-ra', '--dev']

[0xverin]

LGTM.Thanks!

[Kailai-Wang]

Unfortunately this PR breaks the case where only the parachain is launched without worker, because LITENTRY_PARACHAIN_DIR can only be set from py.

e.g.
make launch-docker-rococo will cause the generated files to be written to /tmp/ directly
make clean-docker-rococo will error out due to unset env - and I don't know how to set this var even if I want to fix it - as the artefacts are located under root /tmp/ :(

make clean-docker-rococo
./scripts/clean-local-docker.sh: line 11: LITENTRY_PARACHAIN_DIR: parameter null or not set
make: *** [Makefile:158: clean-docker-rococo] Error 1

I think we need to get it working.

Other things to check:

• binary mode should work too
• multiple copies of worker + parachain should work at the same host