Support non-encrypted variables in ROFL manifest yaml

[martintomazic]

Part of #2248.

What

Keys that are part of the rofl instance metadata and start with .env prefix are passed as part of the env file during rofl containers init, like is currently done for the rofl secrets.

E2E testing

Created simple tdx instance that printed container secrets, normal secrets, and "public" variable using .env metadata convention above. Used local build of rofl containers, and tested on the Sapphire testnet.

Consideration

Like with secrets we expect the admin to not shoot itself by e.g.:

• Setting values that contains new line character.
• Non posix compliant variables.

Follow-up

Alternative solution from #2248 (comment) can be done as follow-up without being breaking, and will be in fact complementary.

[netlify]

✅ Deploy Preview for oasisprotocol-oasis-sdk canceled.

Name	Link
🔨 Latest commit	b88002f
🔍 Latest deploy log	https://app.netlify.com/projects/oasisprotocol-oasis-sdk/deploys/6a45174afb757f00074dbaa2

[codecov]

Codecov Report

❌ Patch coverage is 36.36364% with 14 lines in your changes missing coverage. Please review.
✅ Project coverage is 51.35%. Comparing base (471d7cd) to head (b88002f).

Files with missing lines	Patch %	Lines
rofl-containers/src/main.rs	0.00%	10 Missing ⚠️
rofl-containers/src/secrets.rs	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2481      +/-   ##
==========================================
- Coverage   51.35%   51.35%   -0.01%     
==========================================
  Files         237      237              
  Lines       17236    17251      +15     
==========================================
+ Hits         8852     8859       +7     
- Misses       8324     8332       +8     
  Partials       60       60              

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.