Daemonize addon store, timeout web requests (nvaccess#16183)

May fix most cases of nvaccess#16123 and nvaccess#16122

Summary of the issue:
requests.get has no default timeout, meaning a connection may hang until it is closed by the server.
The add-on store uses requests with no timeout to fetch data from the add-on store, and download add-ons.
This can cause threads to hang, preventing NVDA from exiting correctly.

Update check also has similar risks with usage of urllib like requests.

Many threads started in NVDA should also be daemonized.

Description of user facing changes
NVDA should exit properly in more cases, make installs safer

Description of development approach
Add timeouts for web requests and daemonize all threads in NVDA.

user_docs/en/changes.t2t

@@ -339,6 +339,14 @@ Use ``bdDetect.DeviceType.*`` instead. (#15772, @LeonarddeR).
 -
 
 
+= 2023.3.4 =
+This is a patch release to fix an installer issue.
+
+== Bug Fixes ==
+- Fixed bug which caused the NVDA process to fail to exit correctly.
+When running the installer, this resulted in the installation entering an unrecoverable state. (#16122, #16123)
+-
+
 = 2023.3.3 =
 This is a patch release to fix a security issue.
 Please responsibly disclose security issues following NVDA's [security policy https://github.com/nvaccess/nvda/blob/master/security.md].