analyzer: update dot shorthand diagnostic to mention static scope

[console-log-life]

Summary

This PR improves the diagnostic message for dot shorthand expressions in the analyzer. The goal is to address the misleading "no context type" message as discussed in #62863.

The Problem

Previously, when a dot shorthand was used with types like dynamic, void, or certain Record types, the analyzer reported:

"A dot shorthand can't be used where there is no context type."

As pointed out by the team, this is inaccurate. A context type (like dynamic) does exist, but it is a type that lacks a static scope, which is required for the dot shorthand to resolve members.

Changes Made

• Updated pkg/analyzer/messages.yaml: Changed the problemMessage for dotShorthandMissingContext to accurately reflect the "static scope" requirement.
• Improved Documentation: Revised the Description and Example sections in the YAML file to explain that the issue isn't just a missing type, but a type that doesn't support static member lookup.
• Enhanced Common Fixes: Added clearer guidance on how to fix the error by providing a context type with a static scope (like a Class or Enum).
• Formatting: Carefully maintained YAML indentation and used backticks for code references to ensure the PR meets SDK contribution standards.

Verification

This change correctly covers the edge cases where a context type is present but lacks static scope:

• fd(.hash) where context is dynamic.
• fv(.hash) where context is void.
• fr(.hash) where context is a Record.

Fixes #62863

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[copybara-service]

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[bwilkerson]

Please see the feedback on the Gerrit CL at https://dart-review.googlesource.com/c/sdk/+/489900.