Implement UniDataTable helper

[warpech]

Implement UniDataTable helper for the custom element <uni-data-table> (development of which is tracked in https://github.com/Starcounter/uniform.css/issues/112)

UniDataTable can be used for:

• read-only tables where each row is a view-model. Typically one column will have a link to a detail page about that row
• editable CRUD table where each row is a view-model

The row view-models can be bound to database objects.

cc @joozek78

[warpech]

Requirements previously stated by @miyconst in https://github.com/Starcounter/RebelsLounge/issues/224#issuecomment-349266838. Not all of them should be implemented in the first phase, but we should keep in mind to approach most of them eventually.

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In Entity Framework using a custom made server side + client side library I am able to make a fully functional CRUD data grid with pagination, column filters, column sorting, and all the features described below within half an hour. The same thing in Starcounter would require at least a few days. Any business system, CRM or anything like that contains multiple CRUD pages, and spending for a few days per page is simply way too expensive.

Starcounter should have an easy way to implement fully functional CRUD page over a data table within an hour.

The proposed solution should have:

• Server side pagination.
• Server side ordering.
• Server side filtering.
• Ability to delete records with default or custom confirmation text.
• Ability to create and edit records in a modal dialog box.
• Basic validation during creation/edition.
• Support for all possible column types: text, textarea, number, checkbox, select, date, datetime.
• Ability to change columns order.
• Ability to change columns size.
• Ability to hide/show grid columns.
• Ability to customize columns with custom template.
• Ability to have show only or edit only columns, first are visible in the data grid only, latest are visible in the edit/create dialog box only.
• Ability to print a printable version of the data grid without anything extra on the page.
• Ability to export data grid into an MS-Excel document. The export should respect grid filters.
• Ability to enable or disable any of the specified features.
• Ability to subscribe to numerous events during the component life time and either cancel it or perform some extra actions.

[warpech]

Agreed on the yesterday meeting between: @PatrykSzwer, @joozek78, @tomalec, @platosha and me:

In C# there will be a way to declare columns in order to use them for sorting, filtering, etc. These columns will be a source of input for uni-data-table, but not the exclusive source of input (the other being <uni-data-table-column>.

The columns defined by C# will render as readonly text by default. If a different rendering is needed for presentation, the renderer can be overridden in <uni-data-table-column property-name=""> where the value of property-name attribute matches the identifier of the column.

@PatrykSzwer and @joozek78 will propose changes to the view-model, defined in https://github.com/Starcounter/uniform.css/blob/master/components/uni-data-table/README.md

[warpech]

Closing as done in https://github.com/Starcounter/Starcounter.Uniform/tree/1.0.0

The features from https://github.com/Starcounter/Starcounter.Uniform/issues/3#issuecomment-400352936 shipped so far:

• Server side pagination.
• Server side ordering.
• Server side filtering.
• By default renders column values as text. Other rendering options, including user input are defined in HTML by the app author
• Ability to customize columns with custom template.

Anyone who wants more features implemented, please open an issue for a particular feature.