sql/parser: add timestamptz alias for timestamp data type

[dt]

Our current 'timestamp' datatype has the same behavior as postgres' timestamptz type:
it accepts strings containing an offset and includes that offset when calculating a utc timestamp, and when returned to the client has an offset (usually 0).

Fixes #5865.

---

This change is

[petermattis]

---

Review status: 0 of 4 files reviewed at latest revision, 1 unresolved discussion.

---

sql/parser/sql.y, line 2722 [r1] (raw file):
Some of the other *Type structures contain a Name field so that we can perfectly round-trip the SQL. See FloatType and StringType for examples.

---

Comments from Reviewable

[RaduBerinde]

---

Review status: 0 of 4 files reviewed at latest revision, 1 unresolved discussion, some commit checks pending.

---

Comments from Reviewable

[dt]

Review status: 0 of 4 files reviewed at latest revision, 1 unresolved discussion, some commit checks pending.

---

sql/parser/sql.y, line 2722 [r1] (raw file):
hm, do we need this to roundtrip? As indicated in the test, I was thinking we'd just normalize it to TIMESTAMP all the time, at least as long as it is just an alias (in the future we might find a client actually wants a timestamp with no offset returned and it'll actually be different behavior)

---

Comments from Reviewable

[petermattis]

Review status: 0 of 4 files reviewed at latest revision, 1 unresolved discussion, some commit checks pending.

---

sql/parser/sql.y, line 2722 [r1] (raw file):
I don't have a specific use case for needing the round-tripping, yet I think we should err on the side of doing so when it isn't difficult.

---

Comments from Reviewable

[dt]

Review status: 0 of 6 files reviewed at latest revision, 1 unresolved discussion.

---

sql/parser/sql.y, line 2722 [r1] (raw file):
Done.

---

Comments from Reviewable

[petermattis]

Review status: 0 of 6 files reviewed at latest revision, 1 unresolved discussion.

---

sql/parser/sql.y, line 2722 [r1] (raw file):
I was imagining TimestampType{Name: "TIMESTAMPTZ"}, but this works too.

---

Comments from Reviewable