Enforce whitespace checking for additional source files

Currently jfx .jcheck/conf file is configured to check following files:

.java, .c, .h, .cpp, .hpp, .cc, .jsl, .fxml, .css, .m, .mm, .frag, .vert, .hlsl, .metal, .gradle, .groovy, .g4, .stg

With WebKit we add several other file extensions in repository which are not added in jcheck. We should evaluate those and consider including in jcheck
Few extensions are : xcconfig, def, json, js, yaml, idl, sh, pl, rb, asm, pm
The above list is not complete. It is the extracted from the files that were updated in WebKit 613.1 update and have trailing white spaces.