[FIX] spreadsheet: force light theme

Currenlyt, when using dark theme, spreadsheet is a mess. It's mostly
light theme, with some dark theme elements (mostly coming from odoo
components). There's even inputs where the text is white on a white
background.

o-spreadsheet code isn't prepared to handle dark theme. At all.
There are hardcoded colors everywhere.

Until we have a proper way to handle dark theme (use overridable scss
variables, rely on bootstrap), we force light theme for all elements
inside o-spreadsheet, including odoo components.

The css rules aren't pretty, but at least the spreadsheet is usable.

opw-3329765

closes odoo/odoo#123359

X-original-commit: 37a5f6a5b4b8ecbacf7a8ce4be822c6f348eb5da
Signed-off-by: Rémi Rahir (rar) <rar@odoo.com>

addons/spreadsheet/static/src/o_spreadsheet/o_spreadsheet_extended.dark.scss

@@ -0,0 +1,26 @@
+// Force light theme for everything in o-spreadsheet until
+// we have the proper scss tool chain to support dark theme properly
+// in the library
+.o-spreadsheet {
+  .o-filter-menu {
+      background-color: #fff !important;
+  }
+  .o_field_tags .badge {
+      background-color: #fff !important;
+      color: #777 !important;
+  }
+  .o_field_selector_chain_part {
+      background: #f6f7fa !important;
+      border-color: #d5dae8 !important;
+  }
+  input {
+      color: #333 !important;
+  }
+  .o_input {
+      color: #777 !important;
+  }
+  .o_domain_leaf_info {
+      background: #f6f7fa !important;
+      border-color: #d5dae8 !important;
+  }
+}