popup.html: add extra saccades styling options under saccades color #129

[rezwan-hossain]

• add extra options in saccades color. The extra options will be saccades-solid-line, saccades-dash-line, saccades-dotted-line, saccades-strickthrough-line
• give the options the same value as the text it shows
• change saccades color label to saccades style

[asieduernest12]

thanks @rezwan-hossain you completed task 1 and task 2 correctly.
Originally, I was expecting the new option additions to be added as part of Saccade colors which means they would have served as extra saccades color alternatives
The final task was to change the Saccades color label to say saccades styles to reflect new new purpose.

Fortunately by you missing to complete task 3. I have realized it is better to keep the Saccades color while providing the saccades styles as a different feature.

Very nice work.