Allow copying data pointed to by relocations in the data view

[LagoLunatic]

Currently the data view only allows you to copy the name and virtual address of symbols pointed to relocations. This means that strings cannot be copied if the relocation is inside data, even though objdiff allows copying strings pointed to by relocations in code.

[LagoLunatic]

Currently the code relies on having an instruction to guess the data type by the load or store instruction:

objdiff/objdiff-core/src/arch/ppc/mod.rs

Lines 370 to 374 in 9c1dad4

	let opcode = powerpc::Opcode::from(resolved.ins_ref.opcode);
	if let Some(ty) = flow_analysis::guess_data_type_from_load_store_inst_op(opcode) {
	// Numeric type.
	return Some(ty);
	}

So for the data view, it won't be possible to guess most data types, but strings specifically should still be possible since they don't rely on having an instruction. But the code will need to be refactored a bit so that the instruction is optional.