refactor(templates): Bootstrap utilities instead of the upstream rules that redid them

webvirtcloud.css still carried the upstream panel's rules for what
Bootstrap 5.3 has as utilities and components:
- the page's bottom space (body padding) is pb-5 on base.html's body,
  and the console page no longer has to undo it;
- the VM page's action tabs (.action-button, .action-block with a
  fixed 65px width) are text-center with a d-block icon; its tab panes
  (#power ... #undefine, one rule each) mt-3;
- the bordered sub-tab panes (.tab-pane-bordered, a fixed #eee border
  that dark themes could not change) border border-top-0 p-3;
- the search box and header buttons (.search, .btn-header) m-1 and
  mt-1; the SSH key select (.keyselect) a form-select;
- the boot order list (.multipleselect, fixed size, #c0c0c0 border) a
  list-group of form-check-input items; its unused .multipleselect-on
  goes;
- table cells centred by a global rule are align-middle on each table.
Two rules against Bootstrap's behaviour go: menus opened on hover on
wide screens (Bootstrap opens them on a click, and keyboard and touch
users had no hover), and "a { outline: 0 }", which hid the keyboard
focus ring.

The paragraph and page-header margins and the 900px container stay
for a separate change: they set every page's layout.

admin/templates/admin/group_list.html

@@ -6,7 +6,7 @@
 {% block content %}
 <div class="row">
     <div class="col-lg-12">
-        <a href="{% url 'admin:group_create' %}" class="btn btn-success btn-header float-end" title="{% trans "Create Group" %}">
+        <a href="{% url 'admin:group_create' %}" class="btn btn-success mt-1 float-end" title="{% trans "Create Group" %}">
             {% bs_icon 'plus-circle-fill' %}
         </a>
         {% include 'search_block.html' %}
@@ -23,7 +23,7 @@
     {% else %}
         <div class="col-lg-12">
             <div class="table-responsive">
-                <table class="table table-striped table-hover">
+                <table class="table table-striped table-hover align-middle">
                     <thead>
                         <tr>
                             <th scope="col">{% trans "Group Name" %}</th>

admin/templates/admin/logs.html

@@ -32,7 +32,7 @@
             </div>
         {% else %}
             <div class="table-responsive">
-                <table class="table table-hover">
+                <table class="table table-hover align-middle">
                     <thead>
                         <tr>
                             <th scope="col">#</th>

admin/templates/admin/tombstone_list.html

@@ -21,7 +21,7 @@
     {% else %}
         <div class="col-lg-12">
             <div class="table-responsive">
-                <table class="table table-striped table-hover">
+                <table class="table table-striped table-hover align-middle">
                     <thead>
                         <tr>
                             <th scope="col">{% trans "Name" %}</th>

admin/templates/admin/user_list.html

@@ -9,7 +9,7 @@
 {% block page_heading %}{{ title }}{% endblock page_heading %}
 
 {% block page_heading_extra %}
-<a href="{% url 'admin:user_create' %}" class="btn btn-success btn-header float-end" title="{% trans "Create User" %}">
+<a href="{% url 'admin:user_create' %}" class="btn btn-success mt-1 float-end" title="{% trans "Create User" %}">
     {% bs_icon 'plus-circle-fill' %}
 </a>
 {% include 'search_block.html' %}
@@ -26,7 +26,7 @@
     {% else %}
         <div class="col-lg-12">
             <div class="table-responsive">
-                <table class="table table-striped table-hover">
+                <table class="table table-striped table-hover align-middle">
                     <thead>
                         <tr>
                             <th scope="col">{% trans "Username" %}</th>