Fix PKCS#7 SignedData parsing for non-OCTET_STRING content types

[cconlon]

Description

wolfSSL failed to parse PKCS#7 SignedData bundles where the encapsulated content was a SEQUENCE (per PKCS#7 "ANY" type) rather than OCTET_STRING (per CMS spec). This affected parsing of Microsoft Authenticode signatures.

This PR fixes the issue by correctly setting the content size for non OCTET_STRING encapsulated contents. It also fixes a degenerate bundle detection issue that showed up when testing the primary issue.

Testing

Tested by building a reproducer based on Issue #9213, then creating a unit test that reproduced the same issue (included here in tests/api/test_pkcs7.c).

Checklist

• added tests
• updated/added doxygen
• updated appropriate READMEs
• Updated manual and documentation

[Copilot]

Pull request overview

This PR fixes a bug in wolfSSL's PKCS#7 SignedData parsing that prevented correct parsing of bundles where the encapsulated content is a SEQUENCE (per original PKCS#7 spec) rather than an OCTET_STRING (per CMS spec). This issue specifically affected Microsoft Authenticode signatures.

• Adds streaming variable initialization for non-OCTET_STRING content types to properly track content size and position
• Fixes degenerate bundle detection by checking signerInfos SET size in addition to the earlier digestAlgorithms check
• Includes comprehensive test coverage for both streaming and non-streaming parsing of PKCS#7 content with SEQUENCE-based encapsulation

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
wolfcrypt/src/pkcs7.c	Initializes streaming variables for PKCS#7 type content, updates degenerate flag detection based on signerInfos SET, and includes minor formatting fixes
tests/api/test_pkcs7.h	Adds declaration and test macro for new test function test_wc_PKCS7_VerifySignedData_PKCS7ContentSeq
tests/api/test_pkcs7.c	Implements comprehensive test with hand-crafted PKCS#7 SignedData bundle containing SEQUENCE content, testing both streaming and non-streaming verification paths

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[cconlon]

Retest this please Jenkins. Caused by PRB-generic-config-parser (Unable to create live FilePath for wolf-linux-cloud-node-knyag5; wolf-linux-cloud-node-knyag5 was marked offline: Connection was broken).