MDL-55167 less: Add some stylelint exceptions to deal with later

1) Use of REM units in course.less
2) CSS hacks (MDL-55142)

theme/bootstrapbase/less/moodle/bootstrapoverride.less

@@ -63,10 +63,14 @@ h4 small {
 .fluid-span (@columns) {
     .fluid-span-full(@columns, @fluidGridColumnWidth, @fluidGridGutterWidth);
 }
+
+// TODO: MDL-55142 remove browser these brwoser hacks:
+/* stylelint-disable declaration-block-no-duplicate-properties, no-browser-hacks */
 .fluid-span-full (@columns, @columnWidth, @gutterWidth) {
     width: (@columnWidth * @columns) + (@gutterWidth * (@columns - 1));
     *width: (@columnWidth * @columns) + (@gutterWidth * (@columns - 1)) - (.5 / @gridRowWidth * 100 * 1%);
 }
+/* stylelint-enable */
 
 /**
  * Implement missing variables, or faulty ones, in Bootstrap rules.

theme/bootstrapbase/less/moodle/course.less

@@ -1,5 +1,6 @@
 /* course.less */
 /* COURSE CONTENT */
+/* stylelint-disable unit-blacklist */
 .section_add_menus {
     text-align: right;
     clear: both;

theme/bootstrapbase/less/moodle/question.less

@@ -74,6 +74,9 @@
     border-bottom: 1px solid #bbb;
     padding: 0.24em 0;
 }
+
+// TODO: MDL-55142 remove browser these brwoser hacks:
+/* stylelint-disable declaration-block-no-duplicate-properties, no-browser-hacks */
 #chooseqtype .alloptions {
     overflow-x: hidden;
     overflow-y: auto;
@@ -85,6 +88,8 @@
     max-height: 60vh;
     width: 60%;
 }
+/* stylelint-enable */
+
 #chooseqtype .qtypeoption {
     margin-bottom: 0;
     padding: 0.3em 0.3em 0.3em 1.6em;

theme/bootstrapbase/less/moodle/responsive.less

@@ -3,6 +3,9 @@
 // Should probably be moved to relevant .less files
 // after 4095 selector issue is solved
 
+// TODO: MDL-55142 remove browser hacks in this file:
+/* stylelint-disable declaration-block-no-duplicate-properties, no-browser-hacks */
+
 @media (min-width: 980px) {
     .dir-rtl .navbar .nav.pull-right,
     .dir-rtl .navbar .logininfo {

theme/bootstrapbase/less/moodle/templates.less

@@ -1,5 +1,7 @@
 /* Styling for mustache templates */
 
+// TODO: MDL-55142 remove browser these brwoser hacks:
+/* stylelint-disable declaration-block-no-duplicate-properties, no-browser-hacks */
 // RTL styles for column templates.
 #grid {
     // A mixin to set styles for the fluid row when RTL language enabled.
@@ -20,6 +22,8 @@
         }
     }
 }
+/* stylelint-enable */
+
 
 // Style for template 3 columns auto.
 .columns-autoflow-1to1to1 {