feat: issue estimations (#696)

* dev: initialize estimation

* dev: issue estimation field in issues and project settings

* dev: update issue estimation logic

apiserver/plane/db/models/issue.py

@@ -8,6 +8,7 @@ from django.conf import settings
 from django.db.models.signals import post_save
 from django.dispatch import receiver
 from django.utils import timezone
+from django.core.validators import MinValueValidator, MaxValueValidator
 from django.core.exceptions import ValidationError
 
 # Module imports
@@ -37,6 +38,9 @@ class Issue(ProjectBaseModel):
         blank=True,
         related_name="state_issue",
     )
+    estimate_point = models.IntegerField(
+        default=0, validators=[MinValueValidator(0), MaxValueValidator(7)]
+    )
     name = models.CharField(max_length=255, verbose_name="Issue Name")
     description = models.JSONField(blank=True, default=dict)
     description_html = models.TextField(blank=True, default="<p></p>")