DemoExtendGrid - add support for PS 1.7.7

[leemyongpakvn]

Problem: function getOption and getColumnById are added since PS 1.7.8, and unavailable in PS 1.7.7

Questions	Answers
Description?	Solution: use their based functions getOptions and getColumns instead (available in both PS 1.7.7, PS 1.7.8 and PS 8.0.0). Note: .grid-mark-row-link is unavailable in PS 1.7.7 so adding .js-submit-row-action for mark click event in PS 1.7.7 is needed
Type?	improvement
BC breaks?	no
Deprecations?	no
Fixed ticket?	Fixes #82
How to test?	Before this PR, module is unable to install on PS 1.7.7; After this PR module is able to install and work on PS 1.7.7, PS 1.7.8 and PS 8.0.0
Possible impacts?	Issue #82 was already fixed by PR 84 by dropping support for PS 1.7.7.