res_pjsip_session: Add overlap_context option.

Adds the overlap_context option, which can be used
to explicitly specify a context to use for overlap
dialing extension matches, rather than forcibly
using the context configured for the endpoint.

ASTERISK-30262 #close

Change-Id: Ibbcd4a8b11402428a187fb56b8d4e7408774a0db

contrib/ast-db-manage/config/versions/f261363a857f_add_overlap_context.py

@@ -0,0 +1,21 @@
+"""add overlap_context
+
+Revision ID: f261363a857f
+Revises: 5a2247c957d2
+Create Date: 2022-12-09 13:58:48.622000
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = 'f261363a857f'
+down_revision = '5a2247c957d2'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    op.add_column('ps_endpoints', sa.Column('overlap_context', sa.String(80)))
+
+def downgrade():
+    op.drop_column('ps_endpoints', 'overlap_context')