Constant METADATA_BLOCK

pub const METADATA_BLOCK: [u8; 28];

The RP2350 chip requires a metadata block. As per section 5.9 from the RP2350 manual, the block contains 2 items:

• An IMAGE_DEF item that declares that the Tock image is executable, runs in Secure mode, for the ARM architecture, for the RP2350 chip.
• A VECTOR_TABLE item that specifies that the vector table is loaded at memory address 0x10000400.