IULRDC-210 DataCORE: more/less vs autolink issue

[rdlebeau]

• javaScript and CSS updates
• The number of characters shown before the 'more' link will now stick to 300 characters instead of expanding to include any links or greater than signs in the text

[aploshay]

Testing locally, I find this fixes a case currently broken on main, where the link starts and ends after the 300 character more/less threshold:

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus in magna ullamcorper, tempus nibhxx
quis, bibendum erat. Praesent vestibulum libero interdum, feugiat sapien in, rhoncus ex. Aliquamxxxx
eleifend, erat ut fermentum blandit, elit orci fermentum quam, finibus dignissim tellus elit vitae 
velit. Nulla turpis duis. https://localhost:3000/concern/data_sets/000000000/edit?locale=en
vitae velit. Nulla turpis duis.

but badly breaks other cases currently working on main:

• where the link text starts before 300, ends after 300:

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus in magna ullamcorper, tempus
nibhxx https://localhost:3000/concern/data_sets/000000000/edit?locale=en vitae velit. Nulla
turpis duis. quis, bibendum erat. Praesent vestibulum libero interdum, feugiat sapien in, rhoncus
ex. Aliquamxxxx eleifend, erat ut fermentum blandit, elit orci fermentum quam, finibus dignissim
tellus elit vitae velit. Nulla turpis duis.

• where the link text starts before 300, ends before 300:

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus in magna ullamcorper, tempus nibhxx
https://localhost:3000/concern/data_sets/000000000/edit?locale=en vitae velit. Nulla turpis duis.
quis, bibendum erat. Praesent vestibulum libero interdum, feugiat sapien in, rhoncus ex. Aliquamxxxx
eleifend, erat ut fermentum blandit, elit orci fermentum quam, finibus dignissim tellus elit vitae
velit. Nulla turpis duis.

[rdlebeau]

I've incorporated the changes from the "revise javascript: search backwards for start tag" commit.