[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)

These methods use the C API pm_newline_list_line_column function to compute line and column numbers.

Public API Changes

Removed items from the public API
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(none)

Changed items in the public API
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(none)

Added items to the public API
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+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

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