atf_comp script generation rework

[ali5h]

Summary

• Rework script pipeline: capture raw output to .out.raw, then run filter to produce .out
• Separate raw input: write tmsgs to .in.raw via heredoc, then run ifilter to produce .in
• Move filter execution into the generated script (previously ran in CompareOutput C++ code)
• Add set -eu -o pipefail to generated test scripts for stricter error handling

New command-line options

• Add -tempdir and -testdir options to make temp/test directories configurable

Replscope and variable fixes

• Restore missing $$ and $timeout variables in Replscope setup
• Fix $compdir -> $bindir rename in script export
• Add new exported variables: $in_raw, $out_raw, $finput, $foutput

New component tests

• atf_comp.Smoke: self-test running atf_comp against a trivial cat command with ifilter (sort) and tfilt (sort -r)
• atf_exp.AcrInteractive: sample interactive test feeding a record to acr -in:- and verifying the response

Coverage improvements

• atf_comp: 0% -> 43.19%
• atf_exp: 0% -> 71.37%