Adds binary info block support.

[thejpster]

Adds support for picotool compatible binary info. Bumps MSRV to 1.77.

$ cargo build --release --example binary_info_demo --features=critical-section-impl,binary-info
   Compiling rp2040-hal v0.10.0 (/home/jonathan/Documents/github/rp-hal/rp2040-hal)
    Finished `release` profile [optimized] target(s) in 2.24s
$ picotool info ./target/thumbv6m-none-eabi/release/examples/binary_info_demo -t elf --all
File ./target/thumbv6m-none-eabi/release/examples/binary_info_demo:

Program Information
 name:          rp2040-hal Binary Info Example
 version:       0.10.0
 web site:      https://github.com/rp-rs/rp-hal
 description:   A GPIO blinky with extra metadata.
 binary start:  0x10000000

Fixed Pin Information
 none

Build Information
 pico_board:        pico
 build attributes:  release

The static variables containing the magic header are optional and gated behind the binary-info flag. This allows people to create their own headers if they so choose.