Slider: Block Page for one scrollbar; Scrollbar width normal

[Cyb10101]

Changes proposed in this pull request:

1. As soon as the sidebar is opened, the content on the main page is blocked so that a second scrollbar does not appear, because the page is no longer scrollable.

2. Why make the scrollbar smaller? I think the content in the slider is long and sometimes the scrollbars are small enough.

How to test the feature manually:

1. Go to main page

2. Click on the gear next to a feed, then manage to open the slider

3. Go to main page

4. Click on "Subscription Management"

5. Click on the gear next to a feed to open the slider

I've tested it, but it's better if someone double checks since I'm new to the project.
Tested in Theme: Origine (and some randomly)

Pull request checklist:

• clear commit messages
• code manually tested
• unit tests written (No tests needed?)
• documentation updated (No documentation needed?)

This shouldn't affect the tests, but since it throws bugs in the edge branch as well, just for documentation.

Test command executed: NO_DOCKER=true make test

/usr/local/bin/php ./bin/phpunit --bootstrap ./tests/bootstrap.php ./tests
PHPUnit 9.5.20 #StandWithUkraine

......................................................FF....FF.  63 / 135 ( 46%)
............................................................... 126 / 135 ( 93%)
.........                                                       135 / 135 (100%)

Time: 00:00.017, Memory: 22.00 MB

There were 4 failures:

1) SearchTest::test__construct_whenInputContainsDate_setsDateValues with data set #1 ('date:2007-03-01T13:00:00Z/P1Y...T2H30M', '1172754000', '1210519799')
Failed asserting that 1210516199 matches expected '1210519799'.

/app/tests/app/Models/SearchTest.php:149

2) SearchTest::test__construct_whenInputContainsDate_setsDateValues with data set #2 ('date:P1Y2M10DT2H30M/2008-05-1...30:00Z', '1172754001', '1210519800')
Failed asserting that 1172757601 matches expected '1172754001'.

/app/tests/app/Models/SearchTest.php:148

3) SearchTest::test__construct_whenInputContainsPubdate_setsPubdateValues with data set #1 ('pubdate:2007-03-01T13:00:00Z/...T2H30M', '1172754000', '1210519799')
Failed asserting that 1210516199 matches expected '1210519799'.

/app/tests/app/Models/SearchTest.php:175

4) SearchTest::test__construct_whenInputContainsPubdate_setsPubdateValues with data set #2 ('pubdate:P1Y2M10DT2H30M/2008-0...30:00Z', '1172754001', '1210519800')
Failed asserting that 1172757601 matches expected '1172754001'.

/app/tests/app/Models/SearchTest.php:174

FAILURES!
Tests: 135, Assertions: 290, Failures: 4.
make: *** [Makefile:64: test] Error 1

[math-GH]

Nice! And welcome!
Please add a line for you in https://github.com/FreshRSS/FreshRSS/blob/edge/CREDITS.md