sdk/rs: add geolocation GeoProbe instruction builders

[ben-dz]

Requires #2961
Resolves: #3013

Summary of Changes

• Add new geolocation module to the Rust SDK with instruction builders for GeoProbe management instructions defined in RFC 16
• Define GeolocationInstruction Borsh-serializable enum with all 13 RFC variants (0-11) plus UpdateProgramConfig (variant 12), preserving correct Borsh variant indices for future GeolocationUser instructions
• Implement 7 builder functions that produce solana_sdk::instruction::Instruction objects: init_program_config, update_program_config, create_geo_probe, update_geo_probe, delete_geo_probe, add_parent_device, remove_parent_device
• Add PDA derivation helpers for program config (["doublezero", "programconfig"]), geo probe (["doublezero", "probe", code]), and geolocation user (["doublezero", "geouser", code]) accounts
• Add borsh as a direct dependency to the SDK crate

Testing Verification

• Unit tests verify correct Borsh variant indices for all in-scope instruction types (variants 0-5 and 12)
• Unit tests validate instruction data payload sizes for fixed-size args
• Builder tests verify correct account counts, writable/signer permissions, pubkey placement, and program ID assignment for all 7 builders
• PDA determinism and uniqueness-by-code tests verify correct seed derivation
• Cross-builder PDA consistency test confirms create and update instructions derive the same probe PDA from matching codes
• make rust-fmt-check passes (nightly rustfmt with imports_granularity=Crate)
• Note: cargo build/cargo test could not run locally due to disk space constraints preventing Rust 1.90.0 toolchain installation; CI will validate compilation and test execution