What does the provided patch do?

Implements vertex coloring for indicator textures, as the documentation already suggests should be possible.

Please provide any additional information below.
-- The following modifications would be required in PitBull4\ModuleHandling\IndicatorModule.lua

local function call_texture_function(self, frame)
    if not self.GetTexture then
        -- no function, let's just return
        return nil
    end
--    local tex
++    local tex, red, green, blue, alpha
    if frame.guid then
--        tex = self:GetTexture(frame)
++        tex, red, green, blue, alpha = self:GetTexture(frame)
    end
    if not tex and frame.force_show and self.GetExampleTexture then
--        tex = self:GetExampleTexture(frame)
++        tex, red, green, blue, alpha = self:GetExampleTexture(frame)
    end
    if not tex then
        return nil
    end

--    return tex    
++    return tex, red, green, blue, alpha
end

--
--
--

function IndicatorModule:UpdateFrame(frame)
    [email protected]@
    expect(frame, 'typeof', 'frame')
    [email protected]@
    
--    local tex = call_texture_function(self, frame)
++    local tex, red, green, blue, alpha = call_texture_function(self, frame)
    if not tex then
        return self:ClearFrame(frame)
    end
    
    local id = self.id
    local control = frame[id]
    local made_control = not control
    if made_control then
        control = PitBull4.Controls.MakeIcon(frame)
        control:SetFrameLevel(frame:GetFrameLevel() + 3)
        frame[id] = control
        control:SetWidth(INDICATOR_SIZE)
        control:SetHeight(INDICATOR_SIZE)
    end
    
    control:SetTexture(tex)
    
++    control.texture:SetVertexColor(red or 1, green or 1, blue or 1, alpha or 1)
    
    control:SetTexCoord(call_tex_coord_function(self, frame, tex))
    
    return made_control
end