feat: add Datadog search script

[robrap]

A search script for searching Datadog
monitors and dashboards.

Implements:

• Duplicate New Relic Dashboard and Alert search script for Datadog #786

Sample script output:

Note: This sample output is slightly out of date.

• It is missing the final output of match counts.
• There may be other minor differences.

% python datadog_search.py --regex "code_owner[^_]"
Searching for regex code_owner([^_]|\b) in all monitors:
.........................................................

...

- 99999999 "LMS missing code owner transactions" ['team:arch-bom', 'service:edx-edxapp-lms', 'operation_name:django.request']
  - match_path: monitor.query
    - match: trace-analytics("@_top_level:1 env:(prod OR edge) service:edx-edxapp-lms -@code_owner:* [email protected]_code:(30* OR 40*) @http.status_code:* operation_name:django.request -resource_name:*404*").rollup("count").by("env,status,service").last("1h") > 10


- 99999999 "LMS unrecognized code_owner_squad" ['team:arch-bom', 'env:prod', 'service:edx-edxapp-lms', 'env:(prod', '-@code_owner:*', '[email protected]_code:(30*', 'operation_name:django.request', '_top_level:1', '_trace_root:1', '[email protected]_code:*', 'http.status_code:*', 'code_owner:*', "code_owner_squad:''", "code_owner_squad:('always-available'", "-@code_owner_squad:('always-available'", 'status:error', '-@code_owner_squad:(always-available', 'env:edge']
  - match_path: monitor.tags[4]
    - match: -@code_owner:*
  - match_path: monitor.query
    - match: trace-analytics("env:(prod OR edge) service:edx-edxapp-lms [email protected]_code:(30* OR 40*) @http.status_code:* operation_name:django.request @code_owner:* -@code_owner_squad:(...

...

Searching for regex code_owner([^_]|\b) in all dashboards:

...

- xxx-xxx-xxx "LMS - missing code_owner" ['team:arch-bom']
  - match_path: dashboard_details.title
    - match: LMS - missing code_owner
  - match_path: dashboard_details.widgets[0]['definition']['content']
    - match: # README
This dashboard displays LMS Transactions and Errors that do not yet have a code_owner.
  - match_path: dashboard_details.widgets[1]['definition']['title']
    - match: LMS Successful Transactions (missing code_owner)
  - match_path: dashboard_details.widgets[2]['definition']['content']
    - match: # LMS Successful Transactions
...

- xxx-xxx-xxx "Edx Studio (CMS) dashboard" ['team:tnl']
  - match_path: dashboard_details.widgets[5]['definition']['requests'][0]['queries'][0]['search']['query']
    - match: status:error @code_owner:*tnl* service:(edx-edxapp-cms OR edx-edxapp-cms-workers)

...

Skipping xxx-xxx-xxx due to error: Invalid value for `x`, must be a value greater than or equal to `0`
...

Author concern:

The original script had not unit tests. I'm ok with that, but are you?

Merge checklist:
Check off if complete or not applicable:

• Version bumped
• Changelog record added
• Documentation updated (not only docstrings)
• Fixup commits are squashed away
• Unit tests added/updated
• Manual testing instructions provided
• Noted any: Concerns, dependencies, migration issues, deadlines, tickets