Expose spimdisasm pad creation options

[andresj-sanchez]

Summary

• Add config options for controlling Spimdisasm autogenerated data, rodata, and BSS/SBSS pad symbols.
• Map the new options to Spimdisasm GlobalConfig.
• Document the new options in the configuration reference.

Thanks to @dreamingmoths and @Mc-muffin for the help.

Context

Spimdisasm exposes options for controlling autogenerated pad symbols:

CREATE_DATA_PADS
CREATE_RODATA_PADS
CREATE_BSS_PADS

This PR exposes those options through splat config as:

create_data_pads: false
create_rodata_pads: false
create_bss_pads: false

This lets projects control whether generated data, rodata, and BSS/SBSS output includes dummy unreferenced pad symbols.

For example, disabling BSS pad creation can fold gaps into the preceding BSS symbol instead of emitting an extra autogenerated pad label:

dlabel some_bss_symbol
 .space 0x08

Instead of:

dlabel some_bss_symbol
 .space 0x04

/* Automatically generated and unreferenced pad */
dlabel D_XXXXXXXX
 .space 0x04

Notes

• create_bss_pads depends on the companion Spimdisasm CREATE_BSS_PADS option.
• This should be merged after the companion Spimdisasm PR or after a Spimdisasm release containing that change.
• Companion Spimdisasm PR: Add option to disable BSS pad symbols Decompollaborate/spimdisasm#205

Testing

• Verified create_data_pads, create_rodata_pads, and create_bss_pads map to the corresponding Spimdisasm GlobalConfig values.
• Ran PYTHONPATH=src python test.py.
• Ran PYTHONPATH=src python test_n64_entrypoints.py.

[andresj-sanchez]

Small correction to the BSS example in the PR description: the intended behavior is not to fold the padding into the previous BSS symbol's .space, since that makes tools like objdiff infer the symbol as larger. The companion Spimdisasm PR was updated to fix this.

Before, with the autogenerated pad label:

dlabel "m_tpcSingleton__27clsSingleton<11clsPfSystem>", weak
    /* 006E69B8 */ .space 0x04

/* Automatically generated and unreferenced pad */
dlabel D_006E69BC
    /* 006E69BC */ .space 0x04

Current behavior with create_bss_pads: false:

dlabel "m_tpcSingleton__27clsSingleton<11clsPfSystem>", weak
    /* 006E69B8 */ .space 0x04
enddlabel "m_tpcSingleton__27clsSingleton<11clsPfSystem>"
    /* 006E69BC */ .space 0x04

So the dummy D_006E69BC label is gone, but the real BSS symbol still keeps its declared 0x04 size.

[AngheloAlf]

Since this uses a feature from a newer spimdisasm version then you need to bump that version in a few places.
src/splat/disassembler/spimdisasm_disassembler.py, pyproject.toml, requirements.txt and a mention in changelog.md.

Would be also nice to mention the new changes in the changelog too