[rust] add Location line/column and chop methods

[sei40kr]

Summary

• Add start_line() method to Location (Rust equivalent of Ruby's Location#start_line)
• Add end_line() method to Location (Rust equivalent of Ruby's Location#end_line)
• Add start_column() method to Location (Rust equivalent of Ruby's Location#start_column)
• Add end_column() method to Location (Rust equivalent of Ruby's Location#end_column)
• Add chop() method to Location (Rust equivalent of Ruby's Location#chop)

Line/column computation is implemented in Rust using binary search on the line offsets array, matching the approach used by the Ruby and Java bindings.

Public API Changes

Removed items from the public API
=================================
(none)

Changed items in the public API
===============================
(none)

Added items to the public API
=============================
+pub const fn ruby_prism::Location<'pr>::chop(&self) -> Self
+pub fn ruby_prism::Location<'pr>::end_column(&self) -> u32
+pub fn ruby_prism::Location<'pr>::end_line(&self) -> i32
+pub fn ruby_prism::Location<'pr>::start_column(&self) -> u32
+pub fn ruby_prism::Location<'pr>::start_line(&self) -> i32

Test plan

• bundle exec rake cargo:test
• bundle exec rake cargo:lint

🤖 Generated with Claude Code

[kddnewton]

Let's wait on #3860 for this.

[kddnewton]

This doesn't exist anymore, because it was renamed. Please rebase.

[froydnj]

The commit message for this explains that these are troublesome for the WASM target...but why are they troublesome, and can that be fixed instead? They really shouldn't be treated any differently than other structures, and it would be better to not maintain these declarations by hand. I trust bindgen more than manual declarations.

[kddnewton]

Agreed, I don't want us manually maintaining parallel structures.

[kddnewton]

Agreed, I don't want us manually maintaining parallel structures.

[sei40kr]

Updated based on review feedback:

• Removed manual C struct declarations as suggested by @froydnj and @kddnewton. Instead of maintaining parallel pm_line_column_t / pm_line_offset_list_line_column declarations in Rust, the line/column computation is now implemented directly in Rust using binary search on the line_offsets array. This matches the approach used by the Ruby and Java bindings.
• Rebased onto main (the pm_newline_list → pm_line_offset_list rename is no longer relevant since we don't call the C function).
• Preserved emit_rerun_hints from @kddnewton's rebase.