[6.x] Float database types fix

[mnabialek]

At the moment it's impossible to change unsigned float/decimal columns to signed using Laravel Blueprint methods. This change fixes the problem (uses unsigned=false by default) and addition allows to pass unsigned state to methods when creating columns.

For consitency same change was done for double however it's impossible to update double colum out of the box using doctribe/dbal.

Proof of problem:

1st migration:

Schema::create('users', function (Blueprint $table) {
    $table->bigIncrements('id');
    $table->integer('a')->unsigned();
    $table->float('b')->unsigned();
    $table->decimal('d')->unsigned();
});

2nd migration:

Schema::table('users', function (Blueprint $table) {
    $table->integer('a')->change();
    $table->float('b')->change();
    $table->decimal('d')->change();
});

Run first migration and then run migrate --pretend as a result you get:

ALTER TABLE users CHANGE a a INT NOT NULL, CHANGE b b DOUBLE PRECISION UNSIGNED NOT NULL, CHANGE d d NUMERIC(8, 2) UNSIGNED NOT NULL

As you see integer column was changed to signed, however float and decimal weren't. After fix result of this is:

ALTER TABLE users CHANGE a a INT NOT NULL, CHANGE b b DOUBLE PRECISION NOT NULL, CHANGE d d NUMERIC(8, 2) NOT NULL

as expected.

[driesvints]

The extra parameters to the method signatures are breaking changes so this is best to be sent to master.

[mnabialek]

@driesvints Do you think anyone overrides Blueprint methods?

[mnabialek]

I've proposed alternative fix for 6.x branch without changing method signatures #30891 . I believe we should not wait with fixes until new major version