Inter-version testing between CURRENT and NEXT node versions

[nikipapadatou]

Implement a test scenario to validate compatibility between different node versions:

1. Start a network of N nodes running version CURRENT.
2. The nodes upload:

• a feed
• an encrypted file
• an erasure coded file

3. Upgrade half (or all) of the N nodes to version NEXT.

The upgraded nodes fetch the feed, encrypted file, and erasure coded file to verify API compatibility and detect potential regressions.