AIP 84: Migrate GET ASSET EVENTS legacy API to fast API

[vatsrahul1001]

Migrating the connexion API for GET ASSETS EVENTS to fastAPI.

Depends on #43783
related: #43845

Swagger Specs

Response JSON

{
"asset_events": [
{
"id": 1,
"asset_id": 1,
"asset_uri": "s3://bucket/key/1",
"extra": {
"foo": "bar"
},
"source_task_id": "source_task_id",
"source_dag_id": "source_dag_id",
"source_run_id": "source_run_id_1",
"source_map_index": -1,
"created_dagruns": [
{
"run_id": "source_run_id_1",
"dag_id": "source_dag_id",
"logical_date": "2020-06-11T18:00:00Z",
"start_date": "2020-06-11T18:00:00Z",
"end_date": "2020-06-11T18:00:00Z",
"state": "success",
"data_interval_start": "2020-06-11T18:00:00Z",
"data_interval_end": "2020-06-11T18:00:00Z"
}
],
"timestamp": "2020-06-11T18:00:00Z"
},
{
"id": 2,
"asset_id": 2,
"uri": "s3://bucket/key/2",
"extra": {
"foo": "bar"
},
"source_task_id": "source_task_id",
"source_dag_id": "source_dag_id",
"source_run_id": "source_run_id_2",
"source_map_index": -1,
"created_dagruns": [
{
"run_id": "source_run_id_2",
"dag_id": "source_dag_id",
"logical_date": "2020-06-11T18:00:00Z",
"start_date": "2020-06-11T18:00:00Z",
"end_date": "2020-06-11T18:00:00Z",
"state": "success",
"data_interval_start": "2020-06-11T18:00:00Z",
"data_interval_end": "2020-06-11T18:00:00Z"
}
],
"timestamp": "2020-06-11T18:00:00Z"
}
],
"total_entries": 2
}

---

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[amoghrajesh]

Looks good to me!

[pierrejeambrun]

Nice. Just a few suggestions

Do you mind rebasing, base branch has been merged, this will make the review easier.

I'll do a final review then.

You just did during my inital review, thanks :) checking again.

[pierrejeambrun]

A few more comments, overall looking good.

[pierrejeambrun]

Great, thanks!

One last small modification needed following #43932 and we can merge