Refactors app delaborator, merging in the projection delaborator, to
support pretty printing with generalized field notation.
Renames option `pp.structureProjections` to `pp.fieldNotation` and adds
sub-option `pp.fieldNotation.generalized` to enable/disable generalized
field notation. Adds `@[pp_nodot]` attribute to permanently disable
using field notation for a given declaration.
For now, the default value of `pp.fieldNotation.generalized` is false
since we need a stage0 update to add `@[pp_nodot]` to some core
definitions (such as `List.toArray`) before updating the tests.
[Zulip
discussion](https://leanprover.zulipchat.com/#narrow/stream/270676-lean4/topic/.60pp.2EgeneralizedFieldNotation.60/near/425856054)
To handle delaborating notations that are functions that can be applied
to arguments, extracts the core function application delaborator as a
separate function that accepts the number of arguments to process and a
delaborator to apply to the "head" of the expression.
Defines `withOverApp`, which has the same interface as the combinator of
the same name from std4, but it uses this core function application
delaborator.
Uses `withOverApp` to improve a number of application delaborators,
notably projections. This means Mathlib can stop using `pp_dot` for
structure fields that have function types.
Incidentally fixes `getParamKinds` to specialize default values to use
supplied arguments, which impacts how default arguments are delaborated.
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Co-authored-by: Sebastian Ullrich <sebasti@nullri.ch>
