Bundle LZMA SDK for .edz extraction; drop 7z CLI dependency (M3)

Replaces the QProcess->7z shim with the public-domain LZMA SDK (23.01) 7-Zip
reader, vendored under sources/import/edz/lzma/ (decode-only subset). New
edzsevenzip.cpp wraps SzArEx_Open/SzArEx_Extract and writes entries via Qt, so
EdzArchive no longer needs an external 7-Zip at runtime. Enables the C language
in CMake for the vendored sources.

Verified: the bundled decoder extracts all three ifm sample .edz and the
generated elements still match the Python oracle exactly (byte-correct decode),
with no 7z on the path.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

sources/import/edz/lzma/Alloc.h

@@ -0,0 +1,71 @@
+/* Alloc.h -- Memory allocation functions
+2023-03-04 : Igor Pavlov : Public domain */
+
+#ifndef ZIP7_INC_ALLOC_H
+#define ZIP7_INC_ALLOC_H
+
+#include "7zTypes.h"
+
+EXTERN_C_BEGIN
+
+/*
+  MyFree(NULL)        : is allowed, as free(NULL)
+  MyAlloc(0)          : returns NULL : but malloc(0)        is allowed to return NULL or non_NULL
+  MyRealloc(NULL, 0)  : returns NULL : but realloc(NULL, 0) is allowed to return NULL or non_NULL
+MyRealloc() is similar to realloc() for the following cases:
+  MyRealloc(non_NULL, 0)         : returns NULL and always calls MyFree(ptr)
+  MyRealloc(NULL, non_ZERO)      : returns NULL, if allocation failed
+  MyRealloc(non_NULL, non_ZERO)  : returns NULL, if reallocation failed
+*/
+
+void *MyAlloc(size_t size);
+void MyFree(void *address);
+void *MyRealloc(void *address, size_t size);
+
+#ifdef _WIN32
+
+#ifdef Z7_LARGE_PAGES
+void SetLargePageSize(void);
+#endif
+
+void *MidAlloc(size_t size);
+void MidFree(void *address);
+void *BigAlloc(size_t size);
+void BigFree(void *address);
+
+#else
+
+#define MidAlloc(size) MyAlloc(size)
+#define MidFree(address) MyFree(address)
+#define BigAlloc(size) MyAlloc(size)
+#define BigFree(address) MyFree(address)
+
+#endif
+
+extern const ISzAlloc g_Alloc;
+
+#ifdef _WIN32
+extern const ISzAlloc g_BigAlloc;
+extern const ISzAlloc g_MidAlloc;
+#else
+#define g_BigAlloc g_AlignedAlloc
+#define g_MidAlloc g_AlignedAlloc
+#endif
+
+extern const ISzAlloc g_AlignedAlloc;
+
+
+typedef struct
+{
+  ISzAlloc vt;
+  ISzAllocPtr baseAlloc;
+  unsigned numAlignBits; /* ((1 << numAlignBits) >= sizeof(void *)) */
+  size_t offset;         /* (offset == (k * sizeof(void *)) && offset < (1 << numAlignBits) */
+} CAlignOffsetAlloc;
+
+void AlignOffsetAlloc_CreateVTable(CAlignOffsetAlloc *p);
+
+
+EXTERN_C_END
+
+#endif