Standardize executable path location

[rennergade]

As of now, lind can execute a cwasm file living anywhere on the hosts filesystem, without regarding its relationship to lind_root. This can cause problems with consistency as seen here, possible security problems, or just lack of a general philosophy .

The simple fixes are just to change the lind-clang script to mv any executable to lind-root, or a relative path from there, and change lind-wasm to only execute things starting from lind-root.

We probably want to consider adding checks at runtime to only accept files with proper paths as well.

[rennergade]

Some first steps here. @DyanB can you handle these:

1. Add line to lind_compile.sh that moves produced executable(s) to LIND_ROOT (or specified subdirectory)
2. Add line to lind_run.sh so that it assumes binary is in path from LIND_ROOT
3. Change test suite so it knows to run files from LIND_ROOT