DoProtoId: skip pre-version banner lines

[ejohnstown]

1. Client skips non-SSH lines (RFC 4253 4.2); server rejects them
2. 255-byte per-line cap and 10-line cap (WOLFSSH_MAX_BANNER_LINES)
3. 28 test vectors plus scripted-IO mock for WANT_READ resumption

Issue: F-606

[Copilot]

Pull request overview

Updates SSH protocol identification parsing to follow RFC 4253 §4.2 by allowing clients to skip pre-version banner lines (while servers reject them), with explicit caps to prevent banner-based stalling.

Changes:

• Add a configurable cap on pre-version banner lines (WOLFSSH_MAX_BANNER_LINES) and persist a banner-line counter in handshake state.
• Replace the previous identification line read logic with a line-oriented reader enforcing the 255-octet per-line limit and supporting CRLF/LF terminators.
• Add unit tests (including scripted non-blocking WANT_READ resumption) covering banner handling, limits, and error mappings.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
wolfssh/internal.h	Adds WOLFSSH_MAX_BANNER_LINES, tracks banner line count in HandshakeInfo, and exposes wolfSSH_TestDoProtoId() for internal tests.
src/internal.c	Implements GetInputLine() (255-byte cap) and updates DoProtoId() to skip/limit banner lines per endpoint role and to be robust across WANT_READ retries.
tests/unit.c	Adds comprehensive DoProtoId unit tests plus a scripted IO recv mock to validate WANT_READ resumption and banner-line cap enforcement.

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[wolfSSL-Fenrir-bot]

Fenrir Automated Review — PR #959

Scan targets checked: wolfssh-bugs, wolfssh-src

No new issues found in the changed files. ✅