shellcheck: clean up quoting and sourcing warnings in basics.sh

Address a batch of ShellCheck findings in Runner/utils/basics.sh by:
- adding targeted SC1091 annotations for runtime-sourced helper files
- quoting path and argument expansions where safe
- replacing legacy backticks with
- simplifying useless echo-based assignments
- converting indirect 127 checks to direct command tests
- cleaning up arithmetic expansions and x-prefixed comparisons

These changes are mechanical and do not alter the intended basics.sh runtime flow.

Signed-off-by: Srikanth Muppandam <smuppand@qti.qualcomm.com>

Author: smuppand