Allow crate-level program(name/address) to override the primary program

[lorisleiva]

This PR lets a crate-level #![codama(program(name = ..., address = ...))] directive override the primary program's identity, with either argument optional so omitted fields fall back to the crate defaults (the Cargo.toml package name and the declare_id! / package.metadata.solana.program-id address).

Scope-aware program(...) directive

The directive's required arguments now depend on where it is attached:

Scope	name	address
Crate root (#![codama(program(...))] in lib.rs)	optional	optional
File-module (#![...] in foo.rs)	required	required
Module block (#[codama(program(...))] mod { .. })	required	required
Item (instruction / account / event / …)	required	required

Only the crate root overrides an existing default program, so it may omit either field. Every other scope declares a distinct program that has no defaults to fall back on, so both remain required.

To tell the crate root apart from a file-module (both previously mapped to AttributeContext::File), this adds a new AttributeContext::Crate variant, built explicitly by CrateKorok::parse.

Behaviour

• ProgramDirective's name/address become Option; update_or_wrap_program_node only overrides the fields the directive actually set.
• SetProgramMetadataVisitor applies the crate-level directive before the Cargo.toml / declare_id! fallbacks, so an explicit value wins while unset fields still resolve from the manifest.
• The additional-program separation for item / module / file-module scopes is unchanged.

Tests

• Scope-aware parsing: crate scope accepts program(name = ..), program(address = ..) and program(); item scope still errors when either is missing.
• Visitor-level overrides: name-only, name-over-manifest, and address override.

Follow-up

Enables renaming a program without touching the crate name, e.g. #![cfg_attr(feature = "codama", codama(program(name = "associatedTokenAccount")))] in the associated-token-account interface crate, which will be done once a version carrying this change is released.