Update the default log provider to SeriLog instead of Log4Net

[ihouvet]

Overview

The Shesha starter application comes with Log4Net configured by default. This is somewhat outdated and should be changed to Serilog.

Acceptance Criteria

1. Shesha starter application configured with Serilog by default.
   1. log4net.config Removed from starter project
   2. AppSettings to come with default Serilog configuration.
2. Since Logger object is exposed via the AspNetBoilerplate infrastructure in most cases (e.g. on AppServices and DomainServices) and it uses Log4Net by default will probably have to change default configuration there (see: https://aspnetboilerplate.com/Pages/Documents/Logging)
3. Shesha documentation is updated. Should mostly consist of:
   1. Explanation that using Serilog
   2. Basic how to, for example how to change logging level and sinks
   3. References to Serilog documentation.

Useful Resources:

1. https://youtu.be/QjO2Jac1uQw?si=w8KSuytxSzEeEfja
2. https://youtu.be/nVAkSBpsuTk?si=nA5QjJqX5FO7Gtx8