Fix system settings label and description fields alignment in RTL mode

[nadavkav]

Before fix:

After fix:

@media (min-width: 992px)
.dir-rtl {
.form-item .form-label {float: right;}
.mform .fitemtitle, .form-label {text-align: left;}
.form-item .form-description {margin-right: 33.33333333%;}
}

[gjb2048]

Is this related to #273?

[gjb2048]

I think this is fixed if 'moodle-rtl.css' is used but the block flipping logic has gone?

[nadavkav]

I was not brave enough to test #273?

But I think I found it in moodle-rtl.css

.form-item .form-description {margin-right: 33.33333333%;}
https://github.com/bmbrands/theme_bootstrap/blob/master/style/moodle-rtl.css#L16974

not completely sure about:
.mform .fitemtitle, .form-label {text-align: left;}
.form-item .form-label {float: right;}

https://github.com/bmbrands/theme_bootstrap/blob/master/style/moodle-rtl.css#L16855