feat(c_sharp): support more @function capture (#800)

Property, indexer, operator, conversion operator are special functions
that we should support `@function` captures for them.

Author: sharpchen

queries/c_sharp/textobjects.scm

@@ -45,13 +45,103 @@
     "=>"
     _+ @function.inner)) @function.outer
 
+; method without body(abstract method/decompiled metadata)
+(method_declaration
+  _+
+  ";") @function.outer
+
+(property_declaration
+  accessors: (accessor_list
+    (accessor_declaration
+      body: (block
+        .
+        "{"
+        _* @function.inner
+        "}")) @function.outer))
+
+(property_declaration
+  accessors: (accessor_list
+    (accessor_declaration
+      body: (arrow_expression_clause
+        "=>"
+        _* @function.inner)) @function.outer))
+
+(indexer_declaration
+  accessors: (accessor_list
+    (accessor_declaration
+      body: (arrow_expression_clause
+        "=>"
+        _+ @function.inner)) @function.outer))
+
+(indexer_declaration
+  accessors: (accessor_list
+    (accessor_declaration
+      body: (block
+        .
+        "{"
+        _* @function.inner
+        "}")) @function.outer))
+
+(conversion_operator_declaration
+  body: (block
+    .
+    "{"
+    _* @function.inner
+    "}")) @function.outer
+
+(conversion_operator_declaration
+  body: (arrow_expression_clause
+    "=>"
+    _+ @function.inner)) @function.outer
+
+(operator_declaration
+  body: (block
+    .
+    "{"
+    _* @function.inner
+    "}")) @function.outer
+
+; operator without body(abstract/decompiled metadata)
+(operator_declaration
+  _+
+  ";") @function.outer
+
+(operator_declaration
+  body: (arrow_expression_clause
+    "=>"
+    _+ @function.inner)) @function.outer
+
 (constructor_declaration
   body: (block
     .
     "{"
     _+ @function.inner
     "}")) @function.outer
 
+; constructor without body(metadata)
+(constructor_declaration
+  _+
+  ";") @function.outer
+
+(local_function_statement
+  body: (block
+    .
+    "{"
+    _* @function.inner
+    "}")) @function.outer
+
+(local_function_statement
+  body: (arrow_expression_clause
+    "=>"
+    _+ @function.inner)) @function.outer
+
+(anonymous_method_expression
+  (block
+    .
+    "{"
+    _* @function.inner
+    "}")) @function.outer
+
 (lambda_expression
   body: (block
     .