syz-manager: First Time column is wrong

[dvyukov]

First Time for bugs actually shows Last Time:

We stat description file to get the first time, but we write description file every time we save a crash.

Now that we have "title-stat" file that contains info about all crashes anyway, it would be useful to re-purpose it to store all info we need to render the page, rather than just some small subset of that info so that we still need to check all crash files.
It could contain first time, but also real total count rather than the capped value.
cc @tarasmadan

[a-nogikh]

We stat description file to get the first time, but we write description file every time we save a crash.

If we just overwrite it, its creation time should still stay correct?

syzkaller/pkg/manager/crash.go

Line 253 in 15f6fd0

ret.FirstTime = osutil.CreationTime(stat)