res_pjsip: return all codecs on a re-INVITE without SDP

Currently chan_pjsip on receiving a re-INVITE without SDP will only
return the codecs that are previously negotiated and not offering
all enabled codecs.

This causes interoperability issues with different equipment (e.g.
from Cisco) for some of our customers and probably also in other
scenarios involving 3PCC infrastructure.

According to RFC 3261, section 14.2 we SHOULD return all codecs
on a re-INVITE without SDP

The PR proposes a new parameter to configure this behaviour:
all_codecs_on_empty_reinvite. It includes the code, documentation,
alembic migrations, CHANGES file and example configuration additions.

ASTERISK-30193 #close

Change-Id: I69763708d5039d512f391e296ee8a4d43a1e2148

contrib/ast-db-manage/config/versions/ccf795ee535f_all_codecs_on_empty_reinvite.py

@@ -0,0 +1,37 @@
+"""all_codecs_on_empty_reinvite
+
+Revision ID: ccf795ee535f
+Revises: 539f68bede2c
+Create Date: 2022-09-28 09:14:36.709781
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = 'ccf795ee535f'
+down_revision = '417c0247fd7e'
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects.postgresql import ENUM
+
+AST_BOOL_NAME = 'ast_bool_values'
+# We'll just ignore the n/y and f/t abbreviations as Asterisk does not write
+# those aliases.
+AST_BOOL_VALUES = [ '0', '1',
+                    'off', 'on',
+                    'false', 'true',
+                    'no', 'yes' ]
+
+def upgrade():
+    ############################# Enums ##############################
+
+    # ast_bool_values has already been created, so use postgres enum object
+    # type to get around "already created" issue - works okay with mysql
+    ast_bool_values = ENUM(*AST_BOOL_VALUES, name=AST_BOOL_NAME, create_type=False)
+
+    op.add_column('ps_globals', sa.Column('all_codecs_on_empty_reinvite', ast_bool_values))
+
+def downgrade():
+    if op.get_context().bind.dialect.name == 'mssql':
+        op.drop_constraint('ck_ps_globals_all_codecs_on_empty_reinvite_ast_bool_values', 'ps_globals')
+    op.drop_column('ps_globals', 'all_codecs_on_empty_reinvite')