Merge 'Pragma page size reading' from Anton Harniakou

1) Fix a bug where cli pretty mode would not print pragma results;
2) Add ability to read page_size using PRAGMA page_size;

Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>

Closes #1394

cli/app.rs

@@ -797,7 +797,7 @@ impl<'a> Limbo<'a> {
                         }
                     }
 
-                    if table.header().is_some() {
+                    if !table.is_empty() {
                         let _ = self.write_fmt(format_args!("{}", table));
                     }
                 }

core/translate/pragma.rs

@@ -160,6 +160,9 @@ fn update_pragma(
             // getting here
             unreachable!();
         }
+        PragmaName::PageSize => {
+            todo!("updating page_size is not yet implemented")
+        }
     }
 }
 
@@ -257,6 +260,10 @@ fn query_pragma(
             });
             program.emit_result_row(register, 1);
         }
+        PragmaName::PageSize => {
+            program.emit_int(database_header.lock().page_size.into(), register);
+            program.emit_result_row(register, 1);
+        }
     }
 
     Ok(())

core/vdbe/execute.rs

@@ -1448,7 +1448,6 @@ pub fn op_result_row(
         values: &state.registers[*start_reg] as *const Register,
         count: *count,
     };
-
     state.result_row = Some(row);
     state.pc += 1;
     return Ok(InsnFunctionStepResult::Row);

vendored/sqlite3-parser/src/parser/ast/mod.rs

@@ -1622,6 +1622,8 @@ pub enum PragmaName {
     LegacyFileFormat,
     /// Return the total number of pages in the database file.
     PageCount,
+    /// Return the page size of the database in bytes.
+    PageSize,
     /// returns information about the columns of a table
     TableInfo,
     /// Returns the user version of the database file.