[IMP] web,*: lazy load jSignature lib and extension

The jSignature lib is only used by the NameAndSignature component,
which is not accessible on a many screens. This commit thus
removes the lib and its extension from the bundles, and makes the
NameAndSignature component load it on demand.

Part of task~3439226

closes odoo/odoo#138054

Related: odoo/enterprise#48633
Signed-off-by: Samuel Degueldre (sad) <sad@odoo.com>

addons/web_editor/__manifest__.py

@@ -76,11 +76,9 @@ Odoo Web Editor widget.
             'web/static/lib/bootstrap/js/dist/toast.js',
             'web/static/lib/select2/select2.js',
             'web/static/lib/clipboard/clipboard.js',
-            'web/static/lib/jSignature/jSignatureCustom.js',
             'web/static/src/legacy/js/libs/autocomplete.js',
             'web/static/src/legacy/js/libs/bootstrap.js',
             'web/static/src/legacy/js/libs/jquery.js',
-            'web/static/src/legacy/js/libs/jSignatureCustom.js',
             'web/static/src/legacy/js/core/bus.js',
             'web/static/src/legacy/js/core/class.js',
             'web/static/src/legacy/js/core/dialog.js',