feat: add suggestions & dry-run warnings to lint output (#1702)

## Why

It is possible to run `speakeasy lint` see no warnings and then
generate, which then produces warnings (per target). This isn't ideal
UX.

## What changed?

- `speakeasy lint` now outputs suggestions
- `speakeasy lint` now outputs target-specific build warnings

## Demo



https://github.com/user-attachments/assets/41839ca0-d521-4178-82af-8ccd36411b5f

Author: danielkov