Add ${{context.name}} string substitution

[smoser]

Many of the places where subpkg.name is used now would be even nicer with a context-specific name.

Ie, we have this stanza in wolfi lots of times:

uses: test/ldd-check
with:
  packages: ${{subpkg.name}}

But if we changed the default in test/ldd-check to be 'context.name' then we could replace those with:

uses: test/ldd-check

[dannf]

(approved for diagnoses purposes only)

[smoser]

Well,
commit c5cb1c9 failed "Ensure melange package is reproducible" here. with output:

sha256sum: WARNING: 1 of 1 computed checksums did NOT match
stage3/x86_64/melange-0.0.1-r0.apk: FAILED

But then when I tried to add some help diagnosing what went wrong in 33cb0e1 and dcdadcc the test passed. Log of the successful run is here. the output of the most recent run there is pretty clear success:

stage3/x86_64/melange-0.0.1-r0.apk: OK
PASS: stage2 == stage3 for stage2/x86_64/melange-0.0.1-r0.apk
048cf4111051ce4dbe19d753234655f55701ee06dc59409b6db4d1ea8ad3dd94  stage2/x86_64/melange-0.0.1-r0.apk
048cf4111051ce4dbe19d753234655f55701ee06dc59409b6db4d1ea8ad3dd94  stage3/x86_64/melange-0.0.1-r0.apk

So... I don't know why the one failed, but I would not think it was related to this change.

[dannf]

I support merging w/ the diagnostics until if/when we find out why that failed