Detect stack storage being initialized multiple times

[droe]

When the same stack area is being used as storage for a stack block literal as well as for something else, the plugin gets confused and will fail with a hard to diagnose error, such as:

[ScriptingProvider] Stack block 100004ac0: AssertionError: 
[ScriptingProvider] Traceback (most recent call last):
[ScriptingProvider]   File "/Users/daniel/Library/Application Support/Binary Ninja/plugins/binja-blocks/blocks.py", line 928, in annotate_stack_block_literal
[ScriptingProvider]     bl = BlockLiteral.from_stack(bv, block_literal_insn, block_literal_var, sym_addrs)
[ScriptingProvider]   File "/Users/daniel/Library/Application Support/Binary Ninja/plugins/binja-blocks/blocks.py", line 430, in from_stack
[ScriptingProvider]     return cls(bv, is_stack_block, bl_insn, isa, flags, reserved, invoke, descriptor)
[ScriptingProvider]   File "/Users/daniel/Library/Application Support/Binary Ninja/plugins/binja-blocks/blocks.py", line 448, in __init__
[ScriptingProvider]     assert self.invoke != 0
[ScriptingProvider] AssertionError

Instead of attempting to annotate badly, the plugin should attempt to detect at least some of these situations and refuse to annotate automatically.

Sample: iOS 18.2 /usr/libexec/xpcproxy function at 10000487c has a huge giant mess that we'd like to not touch

Sample: iOS 18.2 /usr/libexec/nanoregistryd function at 10001a2c4 has re-use of the same block literal multiple times that we'd like to keep annotating