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/LzHash.h

@@ -0,0 +1,34 @@
+/* LzHash.h -- HASH constants for LZ algorithms
+2023-03-05 : Igor Pavlov : Public domain */
+
+#ifndef ZIP7_INC_LZ_HASH_H
+#define ZIP7_INC_LZ_HASH_H
+
+/*
+  (kHash2Size >= (1 <<  8)) : Required
+  (kHash3Size >= (1 << 16)) : Required
+*/
+
+#define kHash2Size (1 << 10)
+#define kHash3Size (1 << 16)
+// #define kHash4Size (1 << 20)
+
+#define kFix3HashSize (kHash2Size)
+#define kFix4HashSize (kHash2Size + kHash3Size)
+// #define kFix5HashSize (kHash2Size + kHash3Size + kHash4Size)
+
+/*
+  We use up to 3 crc values for hash:
+    crc0
+    crc1 << Shift_1
+    crc2 << Shift_2
+  (Shift_1 = 5) and (Shift_2 = 10) is good tradeoff.
+  Small values for Shift are not good for collision rate.
+  Big value for Shift_2 increases the minimum size
+  of hash table, that will be slow for small files.
+*/
+
+#define kLzHash_CrcShift_1 5
+#define kLzHash_CrcShift_2 10
+
+#endif