Replace the current file IO solution with one that uses roc buffers

[lukewilliamboswell]

Replaces #278

[lukewilliamboswell]

Not passing ./ci/all_tests.sh for me locally with the following

$ ROC=roc EXAMPLES_DIR=examples/ ./ci/all_tests.sh
<---- snip ---->
+ expect ci/expect_scripts/file-read-buffered.exp
spawn examples/file-read-buffered
file-read-buffered(11081,0x1ed504f40) malloc: double free for ptr 0x12680e200
file-read-buffered(11081,0x1ed504f40) malloc: *** set a breakpoint in malloc_error_break to debug

Error: output was different from expected value.

@faldor20