Do not report misplaced-load lint in WORKSPACE files

[abhinavgautam01]

Fixes #145.

Summary

This PR fixes a false-positive lint warning in Bazel workspace files.

misplaced-load currently warns when a load(...) is not at the top of a file.
That behavior is useful for normal Starlark files, but it is noisy for WORKSPACE / WORKSPACE.bazel, where repository setup calls may legitimately appear before
load(...).

Changes

• Skip FlowIssue::MisplacedLoad for files named:
• WORKSPACE
• WORKSPACE.bazel
• Keep existing misplaced-load behavior unchanged for all other files.
• Add focused tests in starlark/src/analysis/flow.rs:
• test_lint_misplaced_load_workspace
• test_lint_misplaced_load_workspace_bazel

Validation

• cargo test -p starlark test_lint_misplaced_load --lib
• cargo clippy
• cargo build
• cargo test
• cargo bench

[meta-codesync]

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