Make the BP Tools administration screen more consistent with WP Admin appearance

[imath]

Once a tool is performed and the notice message id displayed, we see some lack of consistency with the WordPress administration general appearance:

1. The notice message does not used the width you could find in other administration screens.
2. This notice message also has a bigger height, giving the impression the dismissible button (x) is not vertically aligned.
3. Moreover, it's minor but, the color of the information above the "Repair tools" form (which seems to be an important advice) is lighter than the rest of the text.

I suggest the attached patch to fix the issue. I'm also adding some screenshots (without the patch & with the patch applied).

[imath]

Without

[imath]

With the patch applied

[espellcaste]

Nice work! All good to me! :)

[imath]

In 12739:

Make the BP Tools Admin screen more consistent with WP Admin ones

• the notice message now uses the same width & height than in other administration screens.
• improve the visibility of the advice about not running multiple tools at the same time.
• edit the HTML markup to use existing WordPress styling and save some code lines into our common.css file.

Fixes #8357