Remove the single-purpose Buffer struct from wren_compiler.c and replace it with type-specific ByteBuffer and IntBuffer types generated via a DECLARE_BUFFER macro in wren_utils.h, with shared buffer logic implemented in wren_utils.c using a void* Buffer helper struct. This enables a growable line-number buffer for debug source lines.
Move SymbolTable struct and its associated functions (initSymbolTable, clearSymbolTable, addSymbol, findSymbol, ensureSymbol, getSymbolName) from wren_vm.c and wren_value.h into new wren_utils.c and wren_utils.h files. Rename all functions with wrenSymbolTable prefix for consistent naming convention, update all call sites across compiler, core, debug, and VM files, and relocate MAX_SYMBOLS constant to wren_common.h.
