This new t-set-slot directive is meant to replace t-set when we need to
define the content of a sub slot. All new code should use that
directive.
The old t-set directive is still supported for now, but this should be
removed when we publish Owl 2.0.
Unfortunately, we chose to use the directive `t-set` to define sub slot
contents in a template.
The goal was to reuse a directive for a similar use case: defining sub
template is almost the same as defining a slot content.
Obviously, this introduces a name conflict: the inner content of a
component cannot use t-set t-value anymore (nor t-set with a body
value), since they are interpreted as slot names.
We mitigate the issue here by only interpreting as slot content the
`t-set` statement located immediately below the parent component tag
name and with a body content.
However, a real fix need to introduce an additional directive to resolve
the ambiguity.
In most cases, we just want Component<any, Env>. But since it was so
annoying to have always the type Env, we actually used
Component<any,any> everywhere.
With this commit, the generic types have a default (and their order is
swapped), so we can simply use Component in most cases, and
Component<Props> when we want to type the props.
Géry Debongnie