SpringBoot Makes it easier to customize a Servlet-based web server's mime mappings

Add a new property called 'mime-mappings' under the 'server' property. This is a key-value-map, which is added to the default MimeMappings.

If their is a need to adjust the documentation, just hit me up and I will add this.

See #38902

Comment From: wilkinsona

Thanks for the PR. Can you please use main as the base branch? This would be a new feature so it won't be included in a maintenance branch.

Comment From: BenchmarkingBuffalo

Sure thing, I rebased it on main and fixed the conflicts. closes #38902

Comment From: mhalbritter

Thanks a lot!