fix(types): make time scale parser and tooltipFormat optional

[galshir]

Fixes #12003

Problem

TimeScaleTimeOptions declares every member as required, including time.parser and time.tooltipFormat. Neither option has a default value (see the options table in docs/axes/cartesian/time.md, where both rows have an empty Default column) and both are guarded at runtime:

• TimeScale#parse() only uses the parser when it is a function or a string
• TimeScale#getLabelForValue() falls back to displayFormats.datetime when tooltipFormat is not set

As a result, anyone who annotates a value with the exported TimeScaleTimeOptions type is forced to supply a parser, and there is no sensible value to supply when a date adapter is already configured.

Change

Mark parser and tooltipFormat as optional. All other members do have defaults in TimeScale.defaults, so they stay required.

This is a type-only change and non-breaking: user facing config already goes through DeepPartial, so no existing configuration changes meaning, and widening a required property to an optional one cannot break existing object literals.

Tests

Added test/types/scales/time_options.ts, covering a minimal object without parser/tooltipFormat, plus the string parser and function parser forms.