feat(data-table): allow custom column widths (#1265)

* feat(data-table): allow header column `width`, `minWidth` values

* Run "yarn build:docs"

* test(data-table): assert width, minWidth properties

* docs(data-table): add "Custom column widths" example

docs/src/pages/components/DataTable.svx

@@ -328,6 +328,14 @@ title="Load balancers" description="Your organization's active load balancers."
   ]}"
 />
 
+### Custom column widths
+
+Specify a `width` or `minWidth` property in the `headers` object to customize the width of each column.
+
+A [table-layout: fixed](https://developer.mozilla.org/en-US/docs/Web/CSS/table-layout#values) rule will be applied to the `table` element when using custom widths.
+
+<FileSource src="/framed/DataTable/DataTableHeaderWidth" />
+
 ### Sticky header
 
 Set `stickyHeader` to `true` for the header to be fixed in place.

docs/src/pages/framed/DataTable/DataTableHeaderWidth.svelte

@@ -0,0 +1,19 @@
+<script>
+  import { DataTable } from "carbon-components-svelte";
+</script>
+
+<DataTable
+  headers="{[
+    { key: 'name', value: 'Name', width: '50%', minWidth: '200px' },
+    { key: 'protocol', value: 'Protocol', width: '60px' },
+    { key: 'port', value: 'Port', width: '60px' },
+    { key: 'rule', value: 'Rule', width: '10rem' },
+  ]}"
+  rows="{Array.from({ length: 6 }).map((_, i) => ({
+    id: i,
+    name: 'Load Balancer ' + (i + 1),
+    protocol: 'HTTP',
+    port: i % 3 ? (i % 2 ? 3000 : 80) : 443,
+    rule: i % 3 ? 'Round robin' : 'DNS delegation',
+  }))}"
+/>