feat(escalating-issues): Migration to create GroupForecast table (#45971)

## Objective:

New table to hold the forecasts for archived groups. We will check if a
group's events has exceeded a forecast to bump it into the `escalating`
status.

migrations_lockfile.txt

@@ -6,5 +6,5 @@ To resolve this, rebase against latest master and regenerate your migration. Thi
 will then be regenerated, and you should be able to merge without conflicts.
 
 nodestore: 0002_nodestore_no_dictfield
-sentry: 0392_add_date_uploaded_field_to_bundle
+sentry: 0393_create_groupforecast_table
 social_auth: 0001_initial

src/sentry/migrations/0393_create_groupforecast_table.py

@@ -0,0 +1,53 @@
+# Generated by Django 2.2.28 on 2023-03-22 16:21
+
+import django.db.models.deletion
+import django.utils.timezone
+from django.db import migrations, models
+
+import sentry.db.models.fields.array
+import sentry.db.models.fields.bounded
+import sentry.db.models.fields.foreignkey
+from sentry.new_migrations.migrations import CheckedMigration
+
+
+class Migration(CheckedMigration):
+    # This flag is used to mark that a migration shouldn't be automatically run in production. For
+    # the most part, this should only be used for operations where it's safe to run the migration
+    # after your code has deployed. So this should not be used for most operations that alter the
+    # schema of a table.
+    # Here are some things that make sense to mark as dangerous:
+    # - Large data migrations. Typically we want these to be run manually by ops so that they can
+    #   be monitored and not block the deploy for a long period of time while they run.
+    # - Adding indexes to large tables. Since this can take a long time, we'd generally prefer to
+    #   have ops run this and not block the deploy. Note that while adding an index is a schema
+    #   change, it's completely safe to run the operation after the code has deployed.
+    is_dangerous = False
+
+    dependencies = [
+        ("sentry", "0392_add_date_uploaded_field_to_bundle"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="GroupForecast",
+            fields=[
+                (
+                    "id",
+                    sentry.db.models.fields.bounded.BoundedBigAutoField(
+                        primary_key=True, serialize=False
+                    ),
+                ),
+                ("forecast", sentry.db.models.fields.array.ArrayField(null=True)),
+                ("date_added", models.DateTimeField(default=django.utils.timezone.now)),
+                (
+                    "group",
+                    sentry.db.models.fields.foreignkey.FlexibleForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE, to="sentry.Group", unique=True
+                    ),
+                ),
+            ],
+            options={
+                "db_table": "sentry_groupforecast",
+            },
+        ),
+    ]

src/sentry/models/__init__.py

@@ -42,6 +42,7 @@ from .groupbookmark import *  # NOQA
 from .groupcommitresolution import *  # NOQA
 from .groupemailthread import *  # NOQA
 from .groupenvironment import *  # NOQA
+from .groupforecast import *  # NOQA
 from .grouphash import *  # NOQA
 from .grouphistory import *  # NOQA
 from .groupinbox import *  # NOQA

src/sentry/models/groupforecast.py

@@ -0,0 +1,32 @@
+from django.db import models
+from django.utils import timezone
+
+from sentry.db.models import (
+    ArrayField,
+    BoundedPositiveIntegerField,
+    FlexibleForeignKey,
+    Model,
+    region_silo_only_model,
+)
+
+
+@region_silo_only_model
+class GroupForecast(Model):
+    """
+    Stores the forecast of expected counts of events for a Group
+
+    ``forecast`` will hold an array of integers. The length of the array
+    is the difference between `date_created` and `valid_until`. Each integer
+    maps to the days in the range of `date_created` and `valid_until`.
+
+    """
+
+    __include_in_export__ = False
+
+    group = FlexibleForeignKey("sentry.Group", unique=True)
+    forecast = ArrayField(of=BoundedPositiveIntegerField, null=True)
+    date_added = models.DateTimeField(default=timezone.now)
+
+    class Meta:
+        app_label = "sentry"
+        db_table = "sentry_groupforecast"