Implement deeplink, creating pastes, log deduplication

Summary:
This diff implements the remaining features in the logs plugin:

- deeplinking
- merging duplicate rows

The logs plugin source code has now been reduced from originally `935` to `285` LoC. All optimisation code has been removed from the plugin:

* debouncing data processing
* pre-rendering (and storing!) all rows

Finally applied some further styling tweaks and applied some renames to DataTable / DataSource + types finetuning. Some more will follow.
Fixed a emotion warning in unit tests which was pretty annoying.

Reviewed By: passy

Differential Revision: D26666190

fbshipit-source-id: e45e289b4422ebeb46cad927cfc0cfcc9566834f

desktop/flipper-plugin/src/state/datasource/DataSource.tsx

@@ -108,11 +108,8 @@ export class DataSource<
   output: Entry<T>[] = [];
 
   /**
-   * Returns a direct reference to the stored records.
-   * The collection should be treated as readonly and mutable;
-   * the collection might be directly written to by the datasource,
-   * so for an immutable state create a defensive copy:
-   * `datasource.records.slice()`
+   * Returns a defensive copy of the stored records.
+   * This is a O(n) operation! Prefer using .size and .get instead!
    */
   get records(): readonly T[] {
     return this._records.map(unwrap);
@@ -134,6 +131,18 @@ export class DataSource<
     this.setSortBy(undefined);
   }
 
+  public get size() {
+    return this._records.length;
+  }
+
+  public getRecord(index: number): T {
+    return this._records[index]?.value;
+  }
+
+  public get outputSize() {
+    return this.output.length;
+  }
+
   /**
    * Returns a defensive copy of the current output.
    * Sort, filter, reverse and window are applied, but windowing isn't.