refactor(lsp): store test definitions in adjacency list (#20330)

Previously:
```rust
pub struct TestDefinition {
  pub id: String,
  pub name: String,
  pub range: SourceRange,
  pub steps: Vec<TestDefinition>,
}

pub struct TestDefinitions {
  pub discovered: Vec<TestDefinition>,
  pub injected: Vec<lsp_custom::TestData>,
  pub script_version: String,
}
```
Now:
```rust
pub struct TestDefinition {
  pub id: String,
  pub name: String,
  pub range: Option<Range>,
  pub is_dynamic: bool, // True for 'injected' module, not statically detected but added at runtime.
  pub parent_id: Option<String>,
  pub step_ids: HashSet<String>,
}

pub struct TestModule {
  pub specifier: ModuleSpecifier,
  pub script_version: String,
  pub defs: HashMap<String, TestDefinition>,
}
```

Storing the test tree as a literal tree diminishes the value of IDs,
even though vscode stores them that way. This makes all data easily
accessible from `TestModule`. It unifies the interface between
'discovered' and 'injected' tests. This unblocks some enhancements wrt
syncing tests between the LSP and extension, such as this TODO:
https://github.com/denoland/vscode_deno/blob/61f08d5a71536a0a5f7dce965955b09e6bd957e1/client/src/testing.ts#L251-L259
and https://github.com/denoland/vscode_deno/issues/900. We should also
get more flexibility overall.

`TestCollector` is cleaned up, now stores a `&mut TestModule` directly
and registers tests as it comes across them with
`TestModule::register()`. This method ensures sanity in the redundant
data from having both of `TestDefinition::{parent_id,step_ids}`.

All of the messy conversions between `TestDescription`,
`LspTestDescription`, `TestDefinition`, `TestData` and `TestIdentifier`
are cleaned up. They shouldn't have been using `impl From` and now the
full list of tests is available to their implementations.

0 files changed, 0 insertions, 0 deletions