pgsql: Add tab completion for CREATE SCHEMA in psql

Add tab completion for CREATE SCHEMA in psql

The following patterns are added for CREATE SCHEMA:
- AUTHORIZATION, without a schema name or after a schema name.
- Possible list of owner roles after AUTHORIZATION.
- CREATE and GRANT within the supported set of commands.
- Correct object types supported in an embedded CREATE SCHEMA command.

While on it, this commit adjusts the completion done after CREATE
UNLOGGED:
- Addition of SEQUENCE.
- Avoid suggesting MATERIALIZED VIEW in CREATE TABLE.

Author: Dagfinn Ilmari Mannsåker
Reviewed-by: Suraj Khamkar, Michael Paquier
Discussion: https://postgr.es/m/8735snihmz.fsf@wibble.ilmari.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/c951e9042dd12db80cac4e9a50f198a1eead2036

Modified Files
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src/bin/psql/tab-complete.c | 45 +++++++++++++++++++++++++++++++++++++--------
1 file changed, 37 insertions(+), 8 deletions(-)