Update findClosestByPath to make filter options partial

[ngbrown]

Brief Description

The filter in the options isn't required for findClosestByPath.

Checklists

• Test passed
• Coding style (indentation, etc)
• Edits have been made to src/ files not index.d.ts
• Run npm run dtslint to update index.d.ts

[pyrodogg]

Thanks for the PR. Please address the line comment. Also, add some tests for the newly updated properties in dist/screeps-tests.ts and run npm run dtslint to update the dist/index.d.ts file