Set cursorHeight

[taosimple]

I changed height: 2.5 and the cursor, selected section height all increase to text line height, it seems weird. I try to change cursor height by modify getFullHeightForCaret in fleather source code, but encountered a issue similar to flutter/flutter#145829, hope add cursorHeight option and sync with TextFiled.

FleatherTheme(
            data: defaultTheme.copyWith(
              paragraph: TextBlockTheme(
                style: defaultTheme.paragraph.style.copyWith(fontSize: 20, height: 2.5),
                spacing: VerticalSpacing.zero(),
              ),
            ),
            child: FleatherEditor(
              controller: _editorController,
              focusNode: _focusNode,
              expands: false,
              embedBuilder: _embedBuilder,
            ),
          );