Do not read out-of-boundary when doing base64 encoding

Implement backpressure for fuzzy check

Serialize control commands

In fact, we cannot send multiple commands and read them through the pipe. It has
caused multiple weird issues in the past but I can now see clearly how it should
be done. We should send commands and serialize all requests pending to let them
being sent one by one, after reply for the previous command has been received.

[Minor] Update Bootstrap

Fix error in headers_checks.lua

Support UTF8 flag for the received headers

Fix statfile symbols disabling

Issue: #4919

[Fix] Relearn messages in bayes filter

[Minor] Add selector to get rspamd_hostname

When relearning a message, this script is called twice:

1. With `is_unlearn` true and the old `is_spam` value
2. With `is_unlearn` false and the new `is_spam` value

If `is_unlearn` is true, the code should not increase the value of the hash_key. Decreasing it ensures that it behaves like a fresh learn with the new is_spam value.

Treat relearning from ham to spam the same as relearning from spam to ham. `res` is only set to true if the mail is already learned.

Instead of calling get_hostname() for every processed message, we instead reuse the variable value from rspamd boot time

[WebUI] Prevent navbar layout shift

[WebUI] Add missing handler for file input

[Minor] Cloudmark scores_symbols: convert keys to numeric values

caused by buttons hiding and scroll bar

[Enhancement] Exclude false positives of MIME_DOUBLE_BAD_EXTENSION

[Minor] Increase RDNS_NONE score to 2.0

If we detected extension of the file and this extension is equal to the real extension then we should not pass second extension to check function as it will trigger false positive for MIME_DOUBLE_BAD_EXTENSION.

Add tests for grow_factor

[Test] Fix uploading of test logs when tests are failed

[WebUI] Escape HTML characters in errors history

Rework grow factor