Respect source encoding as defined in pom.xml

[barulheira]

Describe the bug
VS Code assumes all sources are UTF-8, unless defined in setting "files.encoding". It doesn't respect encoding as defined in pom.xml.
In absence of the "files.encoding" setting, the Maven plugin should assume encoding as defined in pom.xml.

To Reproduce
Create a fresh Maven project defining project.build.sourceEncoding as anything but UTF-8, for instance ISO-8859-1.
Create some Java files containing non-ASCII characters.

Expected behavior
VS Code opens Java source files with the correct encoding.

Environments (please complete the following information as much as possible):

• OS: FreeBSD
• VS Code 1.99
• Extension 0.44.0