Dynamic X-axis label based on date granularity

[jesshitchcock]

Currently, the X-axis label in charts always displays the name of the underlying data or timestamp field (e.g., 'Date', 'user_created'), regardless of the selected date granularity.

Feature request:

• Make the X-axis label dynamic so that it updates automatically based on the selected date granularity.
• For example, if the user selects 'Month' granularity, the label should display 'Month' instead of 'Date'.
• Alternatively, display both the field and the granularity, e.g., Date (Month) or user_created (Year).

Why it's needed:

• Improves clarity for users viewing charts, especially when switching between different time grains.
• Reduces confusion when the displayed data does not match the static label.

Example:

• If the user selects 'Year' granularity, the X-axis label should update to 'Year'.
• If the user selects 'Month', it should update to 'Month', etc.

Not a must-have, but would be a nice improvement for user experience.

[linear[bot]]

PROD-1203

[lightdash-bot]

This issue was mentioned by a user in slack: https://lightdash.slack.com/archives/C098WDZUQMR/p1764906543252029?thread_ts=1764906543.252029&cid=C098WDZUQMR