Migrate merge_imports Assist to Use SyntaxFactory

[tareknaser]

This PR is part of #15710 and #18285.

Changes Made

• Followed the steps in Migrate assists to SyntaxEditor #18285 for migration.
• Removed the edits_mut vector from crates/ide-assists/src/handlers/merge_imports.rs
• Added a new SyntaxFactory method whitespace
  • There are no mappings needed as far as I am concerned
  • Currently named whitespace as it mirrors make::tokens::whitespace but tokens_whitespace might be a more fitting name.
• Replaced the edit_in_place::Removable trait with edit_in_place::EditorRemovable (Relevant conversation here)
  • This trait requires a SyntaxEditor instance in the remove method to use instead of ted.
  • Implemented for ast::Use and ast::UseTree
  • Most implementations remain the same, except that I used SyntaxEditor::delete instead of ted::remove and ted::remove_all_iter. Since SyntaxEditor::remove doesn’t exist, I assumed delete would perform the same function—though this might be causing issues.

[tareknaser]

Marking this as a draft for now since I’m running into an error.

---- handlers::merge_imports::tests::test_merge_with_synonymous_imports_1 stdout ----

thread 'handlers::merge_imports::tests::test_merge_with_synonymous_imports_1' panicked at crates/syntax/src/syntax_editor/edit_algo.rs:79:8:

some replace change ranges intersect: [Replace(Token([email protected] "\n\n"), Some(Token([email protected] "\n\n"))), Replace(Node([email protected]), None), Replace(Token([email protected] "\n"), None), Replace(Node([email protected]), Some(Node([email protected])))]

  

---- handlers::merge_imports::tests::test_merge_with_synonymous_imports_2 stdout ----

thread 'handlers::merge_imports::tests::test_merge_with_synonymous_imports_2' panicked at crates/syntax/src/syntax_editor/edit_algo.rs:79:8:

some replace change ranges intersect: [Replace(Token([email protected] "\n\n"), Some(Token([email protected] "\n\n"))), Replace(Node([email protected]), None), Replace(Token([email protected] "\n"), None), Replace(Node([email protected]), Some(Node([email protected])))]

  

---- tests::generated::doctest_merge_imports stdout ----

thread 'tests::generated::doctest_merge_imports' panicked at crates/syntax/src/syntax_editor/edit_algo.rs:79:8:

some replace change ranges intersect: [Replace(Node([email protected]), Some(Node([email protected]))), Replace(Token([email protected] "\n"), Some(Token([email protected] "\n"))), Replace(Node([email protected]), None), Replace(Token([email protected] "\n"), None)]