Homi has new flag *nodekey-dir

[ian0371]

Proposed changes

New flags {c,p,e}n-nodekey-dir has been added to homi. See further comments for a sample input.
With the flags, homi uses the given keys for nodes instead of generating random keys.

Priority for CN keys: cn-nodekey-dir > mnemonic > randomly generated nodekeys
Priority for PN,EN keys: {p,e}n-nodekey-dir > randomly generated nodekeys
(fyi, see mnemonic flag from #1813)

Types of changes

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• Bugfix
• New feature or enhancement
• Others

Checklist

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• I have read the CONTRIBUTING GUIDELINES doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes ($ make test)
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules

Further comments

How to test:

1. Create keys

#!/bin/bash
NUM_CN=1
NUM_PN=2
NUM_EN=4

mkdir -p keys
for i in $(seq 1 $NUM_CN); do
    xxd -l 32 -c 32 -p /dev/urandom | tr -d '\n' > keys/nodekey$i
done

mkdir -p keys_pn
for i in $(seq 1 $NUM_PN); do
    xxd -l 32 -c 32 -p /dev/urandom | tr -d '\n' > keys_pn/nodekey$i
done

mkdir -p keys_en
for i in $(seq 1 $NUM_EN); do
    xxd -l 32 -c 32 -p /dev/urandom | tr -d '\n' > keys_en/nodekey$i
done

2. Run homi

homi --cn-num 1 --pn-num 2 --en-num 4 --cn-nodekey-dir keys/ --pn-nodekey-dir keys_pn/ --en-nodekey-dir keys_en/ docker

3. Run network

cd homi-output
docker compose up