Bootstrap 3 to 5 migration

[radudoros]

This upgrades our use of bootstrap from the old 3 to 5.

• Changed less to sass, bootstrap 5 dropped support for less.
• Redefined old bootstrap 3 classes in a shim file (_bootstrap3_compat.scss) to handle breaking class changes easier.
• Replaces the base-style dependency with clarin-theme.scss. base-style's CLARIN customisation was only ~15 variables (the rest of its variables.less was Bootstrap 3's own defaults), so those are ported directly. The file additionally pins the Bootstrap 3 defaults that Bootstrap 5 changed: rounding, line height, heading scale, container widths, card and pagination styling. This is to have the application render as before rather than as stock Bootstrap 5.
• Upgraded font awesome to a newer version, dropped glyphicon and replaced glyphicon usage with corresponding fontawesome icons

And for JS:

• The vendored Bootstrap Tourist (guided tour) is patched for Bootstrap 5 — it reads popover instances from Bootstrap's registry rather than jQuery data, and Popper 2's offset API differs from Popper 1's.

Addresses #421

[clarin-bot]

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Status	Scan Engine	Critical	High	Medium	Low	Total (13)
⛔	Open Source Security	6	7	0	0	13 issues

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[twagoo]

In general, it looks good. I can compile it out of the box on my machine without any issues.

See below for some small things I found:

Mobile hamburger menu

There is a change in the highlighting of the hovered item in the top menu on mobile. I think the current version looks better.

Production:

PR version:

Record page: placement of the options menu trigger on the handle page 'big link'

This has shifted to the centre, which is unexpected.

Production:

PR version:

Record page: search buttons too big

There appears to be much more padding, which leads to an wonky layout inside the table.

Production:

PR version:

Record page: darkness of rows with gray background

The darker background of the rows with record (technical) details is darker than the current production version, which looks slightly worse in my opinion. Also the contrast might be a bit lower because of this. I would prefer the same shade of gray as on current production.

Search results: lack of spacing below second paginator

"Add to VCR" functionality

• The "+VCR" link in the search results and record page doesn't behave like a normal link (compare production to PR version, i.e. the pointer and the underline)
• An off-looking error box appears in the queue 'popup' after adding an item (running locally)

Pointing right icon

In the modal that is activated by clicking a handle or DOI link in the record page.

I think the font awesome's pointing hand icon looks a bit odd, perhaps hard to decipher. Perhaps replace this with the solid version or replace with angles-right:

solid/hand-point-right

OR

angles-right