Use `assert.strictEqual`/`assert.true`/`assert.false`

The `test` method on regexes does not behave like `match` on strings
for checks if the regex matches when the global modifier (g) is present.

Also adds a unit test on tooltips for sanitizing the same template twice.

Co-authored-by: XhmikosR <xhmikosr@gmail.com>

Be consistent with Popper's name.

Co-authored-by: XhmikosR <xhmikosr@gmail.com>

tests: fix sanitizer test.

The test template does not include a `script` tag so the test always returned true.

allow to pass popper.js configuration for tooltip/popover and dropdown

* Improve code coverage for our Button plugin

* improve coverage for our Alert plugin

* test tooltip update method

* test update and dispose for dropdown

* increase code coverage requirements

When a DOM node is passed to an HTML tooltip, the `title` node is only
moved if it is not already in the tooltip. Otherwise, `empty()` is used
instead of `detach()` before appending the `title` to avoid memory
leaks. If a DOM node is passed to a plain text tooltip, its text is
copied via jQuery `.text()`.

Replaces `.detach()` with `.empty()`, as `.detach()` is almost never
useful but instead leaks memory. The difference between `empty` and
`detach` is that the latter keeps all the attached jQuery events/data.
However, since we do not return the previous children, the user would
have to keep these themselves, thus they can `detach()` if necessary.

This is a port of https://github.com/twbs/bootstrap/pull/14552 to v4.