More optimization chances on class, id and data attributes

[eagletmt]

%span{class: func(x)} is currently compiled into code using Faml::AttributeBuilder.
But we could inline it like dynamic attributes.

Before:

_buf << ("<span".freeze); _buf << (::Faml::AttributeBuilder.build("'", true, class: x)); _buf << ("></span>\n".freeze);

After:

_buf << ("<span".freeze); _buf << do_something_with_class('span', x); _buf << ("></span>\n".freeze);