Add pico_set_modified_binary_type function

[will-v-pi]

This adds a function to create binaries with modified RAM/SCRATCH addresses

For example, to only use SRAM1 so you can power down SRAM0 in your binary you could use

pico_set_modified_binary_type(<my_exe> flash RAM "0x20040000" "256k")

To create a XIP_SRAM only binary you could use

pico_set_modified_binary_type(<my_exe> sram
    RAM "0x13ffc000" "12k"
    SCRATCH_X "0x13fff000" "2k"
    SCRATCH_Y "0x13fff800" "2k")

The existing memmap_blocked_ram.ld could be created using

pico_set_modified_binary_type(<my_exe> flash RAM "0x21000000" "256k")

This adds some tests to kitchen_sink to ensure that these generated linker scripts match the default ones, to prevent them diverging

[kilograham]

this is useful functionality; we need to think about whether this is best as modifying the linker script or injecting as per FLASH_SIZE (either way it should - and i think it is for FLASH_SIZE be modifiable via linker script)

[lurch]

To create a XIP_SRAM only binary you could use

pico_set_modified_binary_type(<my_exe> no_flash
    RAM "0x13ffc000" "12k"
    SCRATCH_X "0x13fff000" "2k"
    SCRATCH_Y "0x13fff800" "2k")

Perhaps it would be nice if you could use symbolic aliases here, rather than having to use hardcoded addresses? 🤷

[lurch]

Maybe this is a first step towards #1547 ?

[will-v-pi]

this is useful functionality; we need to think about whether this is best as modifying the linker script or injecting as per FLASH_SIZE (either way it should - and i think it is for FLASH_SIZE be modifiable via linker script)

I've thought it through a bit more - injecting like FLASH_SIZE wouldn't work, because you might need different injected bits for each binary in your project, whereas FLASH_SIZE is set project-wide as it's fixed for a given board

Instead, I've added separate template linker scripts memmap_sram.template.ld and memmap_flash.template.ld, which are copies of memmap_no_flash.ld and memmap_default.ld respectively with the RAM and SCRATCH regions set to be templated. I've also added tests at compile time to kitchen_sink to ensure these files stay in sync.

These template linker scripts could then be extended further to support #1547 - but I think that's probably best for a second PR, I'd like to just get this functionality in first so you can make SRAM1 or XIP_SRAM binaries

[lurch]

There are a load of double-underscore identifiers (e.g. __logical_binary_start, __embedded_block_end, __binary_info_start) which aren't included in this list. Should they be? 🤷 (I know almost nothing about linker scripts)

[will-v-pi]

This is an identical copy of memmap_default.ld, so changing anything other than the memory regions is outside the scope of this PR - maybe worth pinging @kilograham about tidying up the linker scripts?

[will-v-pi]

This has been superceded by other linker script changes