More flexibility over header formatting

[rowanhemsi]

Describe the solution you'd like
I would like to have more flexibility over how headers are formatted, for example, use different formatting for different column names, or for the units or table notes added to the column headers

Describe alternatives you've considered
Some flexibility is provided by the use of additional_formatting

DoD: The code is updated to allow users to specify custom formatting for individual column headers, units, or table notes within headers. The new functionality supports targeting specific columns or header elements for unique formatting. The implementation integrates with or extends the existing additional_formatting mechanism as appropriate.

[giro090]

From Section 4 of the guidance:

'It is best practice to:

• highlight column headings and row labels by setting the text to bold
• ensure the ‘default’ or ‘automatic’ colour is selected for all text (see the section on ‘Formatting and use of colour’ for more information on why this is important)
  ...
• right align all data within a table and all column headings (except ones above row labels or other text columns – these should be left aligned)'

The same section has guidance on displaying units:

'Ensure it is clearly indicated if your columns use different units. If needed, put the units for your data in rounded brackets after the column heading – for example: ‘Number of people in employment (thousands)’.

It is best to space the information about units so it appears under the column heading text – you can do this by pressing ‘Alt’ and ‘Enter’ at the same time when typing in a cell.'

This task may need a discussion on which additional functionality to include in accordance with these points (e.g. different ways of displaying the units, not adjusting alignment etc.)