Add more relevant logs on error

[jeremyjams]

When enclaves are in debug mode, when something wrong happens, it's hard to understand why.

e.g:
https://core.dev-pool.goerli.iex.ec/tasks/0x47de6470385802f902ca927779fb064f582ebef8634400ecbf1314bb91cf4be7/stdout

[INFO ] 2021-03-09 16:15:26.916 [main] App - Tee worker post-compute started
[INFO ] 2021-03-09 16:15:26.923 [main] FlowManager - ReadComputedFile stage started
[INFO ] 2021-03-09 16:15:27.259 [main] FlowManager - ReadComputedFile stage completed
[INFO ] 2021-03-09 16:15:27.262 [main] FlowManager - ResultDigest stage started [mode:web2]
[ERROR] 2021-03-09 16:15:27.276 [main] ResultUtils - Failed to computeWeb2ResultDigest (hostDeterministicOutputPath missing) [chainTaskId:0x47de6470385802f902ca927779fb064f582ebef8634400ecbf1314bb91cf4be7]
[ERROR] 2021-03-09 16:15:27.276 [main] FlowManager - ResultDigest stage failed (empty resultDigest)

Error logs should be more meaningful.

Ideas: Add infos like tree, ls, cat ..