🌱 Enable comparison for alternative isText implementation

[spencerschrock]

What kind of change does this PR introduce?

Optimization / comparison

• PR title follows the guidelines defined in our pull request documentation

What is the current behavior?

The Binary Artifacts check uses raw.isText, which is inefficient as written.

What is the new behavior (if this is a feature change)?**

The Binary Artifacts still uses raw.isText, but if SCORECARD_COMPARE_ISTEXT is set as an environment variable the result is compared to the implementation in golang.org/x/tools/godoc/util.
This value is set for the release-test worker to gather data.

In the event of a mismatch, a log message will be displayed.

For example, running scorecard on a test repo which has a file with binary data appended after 1024 bytes: https://github.com/spencerschrock/binary-test

SCORECARD_COMPARE_ISTEXT=1 go run main.go --repo spencerschrock/binary-test --checks=Binary-Artifacts

2022/11/01 12:59:23 isText implementations differ for file: script-pkg-managers

• Tests for the changes have been added (for bug fixes/features)

Which issue(s) this PR fixes

Part of #2412

Special notes for your reviewer

Does this PR introduce a user-facing change?

For user-facing changes, please add a concise, human-readable release note to
the release-note

(In particular, describe what changes users might need to make in their
application as a result of this pull request.)

NONE

[codecov]

Codecov Report

Merging #2414 (48c423b) into main (fba72f8) will decrease coverage by 0.00%.
The diff coverage is 40.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2414      +/-   ##
==========================================
- Coverage   40.84%   40.83%   -0.01%     
==========================================
  Files         113      113              
  Lines        8900     8904       +4     
==========================================
+ Hits         3635     3636       +1     
- Misses       5004     5006       +2     
- Partials      261      262       +1     

[laurentsimon]

Thanks for doing all this validation work!

[github-actions]

Integration tests success for
[7a9bbf3]
(https://github.com/ossf/scorecard/actions/runs/3373692517)

[github-actions]

Integration tests success for
[48c423b]
(https://github.com/ossf/scorecard/actions/runs/3374580821)

[spencerschrock]

There are quite a few differences in the worker, so far it seems like the main difference is due to how we treat carriage returns (which are semi frequent).

IsText from golang.org/x/tools/godoc/util allows the\n, \t and \f control characters.
Where as we allow \n, \t and \r.

Modifying IsText from golang.org/x/tools/godoc/util to match our allowed control characters seems to resolve the mismatches I've tested locally. I'll send a follow-up PR later so we can test more in the release test