test: add provides test case from #10973

The actual issue would not have been caught by this, because
it happened only with apkv3 indexes where the adb entry was
decoded incorrectly to apk_dependency structure.

Commit 1ab7f311 fixes the code to work even with the different
decoding of such provides.

And commit 82bcfcc8 fixed the actual decoding to work now same
as in apkv2 side.

test/provides.repo

@@ -148,3 +148,23 @@ I:1
 i:sane-backends
 p:hplip-sane
 
+C:Q1FFN5AdpAOBJWKMR89pp/C66o+OE=
+P:testp
+V:0.1-r0
+S:1
+I:1
+p:foopkg
+
+C:Q1FFN5AdpAOBJWKMR89pp/C66o+FE=
+P:testq
+V:0.1-r0
+S:1
+I:1
+p:foopkg
+
+C:Q1FFpkasfqZAukAXFYbgwt4xAMZWU=
+P:testr
+V:0.1-r0
+S:1
+I:1
+D:foopkg

test/provides16.test

+@ARGS
+--test-repo provides.repo
+add testr
+@EXPECT
+ERROR: unable to select packages:
+  foopkg (virtual):
+    note: please select one of the 'provided by'
+          packages explicitly
+    provided by: testp testq
+    required by: testr-0.1-r0[foopkg]

test/provides17.test

+@ARGS
+--test-repo provides.repo
+add testp testr
+@EXPECT
+(1/2) Installing testp (0.1-r0)
+(2/2) Installing testr (0.1-r0)
+OK: 0 MiB in 0 packages