Add df regions to their own files and only edges to the po file

[angelhof]

Properly serialize the different df regions when spec preprocessing and only add the edges to the po file.

Use by running the following when in $PASH_TOP.

./compiler/preprocessor/preprocessor spec input.sh partial_order.txt

The partial_order.txt file will look like this:

# Partial order files path:
/tmp/pash_BYmDfbB//speculative/partial_order/
0 -> 1
...

where the path is the directory that stores different df regions. For example, region 0 is stored in /tmp/pash_BYmDfbB//speculative/partial_order/0 for that particular example. Furthermore, the arrows show the partial order of df_regions in the original file (for now it is always a sequence, but it can be extended to be a partial order.

TODO: The next step is to add a proper entry point in PaSh that will wait for the scheduler at each runtime invocation. The new entry point should be invoked by a wrapper around PaSh that will first run the scheduler and initialize some environment variables, and then call PaSh.

[github-actions]

OS:ubuntu-20.04
Mon Mar 6 15:02:46 UTC 2023
intro: 2/2 tests passed.
interface: 39/39 tests passed.
compiler: 54/54 tests passed.
agg: 109/109 tests passed.

[github-actions]

OS = Debian 10
CPU = Intel(R) Core(TM) i7-8700 CPU @ 3.20GHz
Ram = 15752
Hash = b1afd46
Kernel= Linux 4.15.0-197-generic x86_64

benchmark	tests	passed	failed	untested	unresolved	unsupported	not_in_use	other_status
posix	494	375	41	31	6	40	1	0
intro	2	2	0	0	0	0	0	0
interface	39	39	0	0	0	0	0	0
compiler	54	54	0	0	0	0	0	0
aggregator	109	109	0	0	0	0	0	0