feat: add some initialization helpers to the sdk

[Stebalien]

This replaces the custom assert macros. Instead of overriding the assert macros, the user would:

1. Call fvm_sdk::initialize() at the top of their actor/tests.
2. Use the default assert macros.

replaces #660

[codecov-commenter]

Codecov Report

Merging #896 (9c7aa10) into master (2705679) will increase coverage by 0.00%.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master     #896   +/-   ##
=======================================
  Coverage   52.01%   52.02%           
=======================================
  Files         124      124           
  Lines       10191    10230   +39     
=======================================
+ Hits         5301     5322   +21     
- Misses       4890     4908   +18     

Impacted Files	Coverage Δ
sdk/src/debug.rs	0.00% <ø> (ø)
sdk/src/lib.rs	12.50% <0.00%> (-12.50%)	⬇️
sdk/src/vm.rs	0.00% <0.00%> (ø)
ipld/encoding/src/cbor.rs	40.67% <0.00%> (+31.30%)	⬆️

[vyzo]

So what happens if the user doesnt call the initializer?

[Stebalien]

The actor will abort with "illegal instruction" instead of a more helpful error message.

[vyzo]

ok, nothing deleterious.