Replace elided lifetimes to explicit lifetimes in trait impl

[taiki-e]

Fixes #106

Currently, these are only applying for function arguments, but this PR change this to also apply to trait and implementor's paths.

impl Trait<'_> for &Type<'_> {}

// converted to:
impl<'impl_life0, 'impl_life1, 'impl_life2> 
    Trait<'impl_life0> for &'impl_life1 Type<'impl_life2> {}