Use RBS type alias for LSP reporter (#3629)

### Motivation

This will allow addons to reference those aliasing types without adding shims.

### Implementation

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### Automated Tests

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### Manual Tests

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Author: st0012

lib/ruby_lsp/test_reporters/lsp_reporter.rb

@@ -12,6 +12,18 @@ module RubyLsp
   class LspReporter
     include Singleton
 
+    # https://code.visualstudio.com/api/references/vscode-api#Position
+    #: type position = { line: Integer, character: Integer }
+
+    # https://code.visualstudio.com/api/references/vscode-api#Range
+    #: type range = { start: position, end: position }
+
+    # https://code.visualstudio.com/api/references/vscode-api#BranchCoverage
+    #: type branch_coverage = { executed: Integer, label: String, location: range }
+
+    # https://code.visualstudio.com/api/references/vscode-api#StatementCoverage
+    #: type statement_coverage = { executed: Integer, location: position, branches: Array[branch_coverage] }
+
     #: bool
     attr_reader :invoked_shutdown
 
@@ -125,7 +137,7 @@ def uri_and_line_for(method_object)
     #       ["Foo", :bar, 6, 21, 6, 65] => 0
     #     }
     # }
-    #: -> Hash[String, StatementCoverage]
+    #: -> Hash[String, statement_coverage]
     def gather_coverage_results
       # Ignore coverage results inside dependencies
       bundle_path = Bundler.bundle_path.to_s