Add extensions for the "application/tar" type

[zhanglin-wu]

Extensions like "tgz" is commonly used, for example, the "npm pack" command generates a .tgz archive.

But these extensions related to the "application/tar" type is not included by mime-db yet, so let's add them here.

[zhanglin-wu]

We can open the source links to see more details about the extensions related to the "application/tar" type:

• https://www.gnu.org/software/tar/
• https://en.wikipedia.org/wiki/Tar_(computing)