Rename submit_form component to page_footer

Submit form was
- a confusing name in itself
- not descriptive, because it also has an optional ‘back’ link

This commit also puts this component in as many pages as possible, stripping
out any hard-coded buttons and links.

It replaces any usage of buttons for ‘back’, because these are links, not
buttons (ie they don’t change any data).

app/templates/views/service-settings/confirm.html

@@ -1,6 +1,6 @@
 {% extends "withnav_template.html" %}
 {% from "components/textbox.html" import textbox %}
-{% from "components/submit-form.html" import submit_form %}
+{% from "components/page-footer.html" import page_footer %}
 
 {% block page_title %}
 GOV.UK Notify | Service settings
@@ -15,7 +15,7 @@ GOV.UK Notify | Service settings
 
     <form method="post">
       {{ textbox('new_name', 'Enter your password', password=True) }}
-      {{ submit_form(
+      {{ page_footer(
         submit_button_text,
         destructive=destructive,
         back_link=url_for('.service_settings')

app/templates/views/service-settings/delete.html

@@ -1,5 +1,5 @@
 {% extends "withnav_template.html" %}
-{% from "components/submit-form.html" import submit_form %}
+{% from "components/page-footer.html" import page_footer %}
 
 {% block page_title %}
   GOV.UK Notify | Service settings
@@ -31,7 +31,7 @@
       </ul>
 
       <form method="post">
-        {{ submit_form(
+        {{ page_footer(
           'Yes, delete ‘{}’'.format(service.name),
           destructive=True,
           back_link=url_for('.service_settings')

app/templates/views/service-settings/name.html

@@ -1,6 +1,6 @@
 {% extends "withnav_template.html" %}
 {% from "components/textbox.html" import textbox %}
-{% from "components/submit-form.html" import submit_form %}
+{% from "components/page-footer.html" import page_footer %}
 
 {% block page_title %}
 GOV.UK Notify | Service settings
@@ -19,7 +19,7 @@ GOV.UK Notify | Service settings
 
       <form method="post">
         {{ textbox('new_name', 'New name', value=service.name) }}
-        {{ submit_form(
+        {{ page_footer(
           'Save',
           back_link=url_for('.service_settings')
         ) }}

app/templates/views/service-settings/request-to-go-live.html

@@ -1,8 +1,8 @@
 {% extends "withnav_template.html" %}
-{% from "components/submit-form.html" import submit_form %}
+{% from "components/page-footer.html" import page_footer %}
 
 {% block page_title %}
-GOV.UK Notify | Service settings
+  GOV.UK Notify | Service settings
 {% endblock %}
 
 {% block maincolumn_content %}
@@ -37,7 +37,7 @@ GOV.UK Notify | Service settings
       </p>
 
       <form method="post">
-        {{ submit_form(
+        {{ page_footer(
           'Request to make service live',
           back_link=url_for('.service_settings')
         ) }}

app/templates/views/service-settings/status.html

@@ -1,5 +1,5 @@
 {% extends "withnav_template.html" %}
-{% from "components/submit-form.html" import submit_form %}
+{% from "components/page-footer.html" import page_footer %}
 
 {% block page_title %}
 GOV.UK Notify | Service settings
@@ -22,7 +22,7 @@ GOV.UK Notify | Service settings
       </p>
 
       <form method="post">
-        {{ submit_form(
+        {{ page_footer(
           'Turn off outgoing messages',
           destructive=True,
           back_link=url_for('.service_settings')