Escalate `missing_required_param` hints to warnings (#8087). (#8096)

Fixes: #8087.

.analysis_options

@@ -24,6 +24,8 @@ analyzer:
   strong-mode:
     implicit-dynamic: false
   errors:
+    # treat missing required parameters as a warning (not a hint)
+    missing_required_param: warning
     # allow overriding fields (if they use super, ideally...)
     strong_mode_invalid_field_override: ignore
     # allow type narrowing

.analysis_options_repo

@@ -25,6 +25,8 @@ analyzer:
   strong-mode:
     implicit-dynamic: false
   errors:
+    # treat missing required parameters as a warning (not a hint)
+    missing_required_param: warning
     # allow overriding fields (if they use super, ideally...)
     strong_mode_invalid_field_override: ignore
     # allow type narrowing

packages/flutter/lib/analysis_options_user.yaml

@@ -25,6 +25,8 @@ analyzer:
     enableSuperMixins: true
   strong-mode: true
   errors:
+    # treat missing required parameters as a warning (not a hint)
+    missing_required_param: warning
     # allow overriding fields (if they use super, ideally...)
     strong_mode_invalid_field_override: ignore
     # allow type narrowing