Parse block type with leb i32 encoding and correct dst dynamic offset for opcode br

[wenyongh]

Fix several issues in wasm loader:

• Parse a block's type index with leb int32 instead leb uint32
• Correct dst dynamic offset of loop block arguments for opcode br
  when copying the stack operands to the arguments of loop block
• Free each frame_csp's param_frame_offsets when destroy loader ctx
• Fix compilation error in wasm_mini_loader.c
• Add test cases of failed issues

This PR fixes issue #3467 and #3468.

[xujuntwt95329]

wasm_loader_pop_frame_csp will also free the param_frame_offsets, should we set it to NULL in wasm_loader_pop_frame_csp?

[wenyongh]

The wasm_loader_push_frame_csp will memset the frame csp with 0, seems no need to set param_frame_offsets to NULL again:

wasm-micro-runtime/core/iwasm/interpreter/wasm_loader.c

Lines 8672 to 8678 in 67638e2

	static bool
	wasm_loader_push_frame_csp(WASMLoaderContext *ctx, uint8 label_type,
	BlockType block_type, uint8 *start_addr,
	char *error_buf, uint32 error_buf_size)
	{
	CHECK_CSP_PUSH();
	memset(ctx->frame_csp, 0, sizeof(BranchBlock));

[xujuntwt95329]

Got it, thanks!

[xujuntwt95329]

LGTM