feat: manage extensions navbar (#2121)

* feat: manage extensions navbar
create now `Manage` spacer in sidebar. and add manage extensions to it
closes #2088
* do not show when no exts
* update cn and jp i18n strings
* rename lnbits-admin-ui component to lnbits-manage, fix its behaviour
* i18n: add Korean language

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Co-authored-by: Pavol Rusnak <pavol@rusnak.io>
Co-authored-by: psychoet <125599543+psychoet@users.noreply.github.com>

lnbits/static/i18n/en.js

@@ -8,7 +8,7 @@ window.localisation.en = {
   channels: 'Channels',
   transactions: 'Transactions',
   dashboard: 'Dashboard',
-  manage_node: 'Manage Node',
+  node: 'Node',
   total_capacity: 'Total Capacity',
   avg_channel_size: 'Avg. Channel Size',
   biggest_channel_size: 'Biggest Channel Size',
@@ -99,13 +99,12 @@ window.localisation.en = {
   disclaimer_dialog:
     'Login functionality to be released in a future update, for now, make sure you bookmark this page for future access to your wallet! This service is in BETA, and we hold no responsibility for people losing access to funds.',
   no_transactions: 'No transactions made yet',
-  manage_server: 'Manage Server',
+  manage: 'Manage',
   extensions: 'Extensions',
   no_extensions: "You don't have any extensions installed :(",
   created: 'Created',
   search_extensions: 'Search extensions',
   warning: 'Warning',
-  manage: 'Manage',
   repository: 'Repository',
   confirm_continue: 'Are you sure you want to continue?',
   manage_extension_details: 'Install/uninstall extension',