Refactor variable usages

[m-1-k-3]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

Fix 400 little bugs :-D

• What is the current behavior? (You can also link to an open issue here)

multiple variable usages are not declared as external/local which results in automatically external declaration,

• What is the new behavior (if this is a feature change)? If possible add a screenshot.

Start fixing

before: [-] Found 554 indirect global variables in all modules
current state: [-] Found 151 indirect global variables in all modules

The following modules are such a big mess that they will be handled in a dedicated PR:

• ./modules/L10_system_emulation.sh - 96 violations
• ./modules/F50_base_aggregator.sh - 55 violations