Set output types

[devdras]

Hi, can you add the option for output types please? Could look something like this:
`async function getTextFromImage(filePath, outputType) {
await (0, _tar.extract)({
file: inputPath,
cwd: '/tmp'
});

if (outputType !== 'stdout' || outputType !== 'txt' || outputType !== 'pdf'|| outputType !== 'hocr'|| outputType !== 'tsv') {
return "BAD_OUTPUT_TYPE"
}

const stdout = (0, _child_process.execFileSync)(outputPath, [filePath, outputType, '-l', 'eng'], {
cwd: '/tmp/tesseract-standalone',
env: {
LD_LIBRARY_PATH: './lib',
TESSDATA_PREFIX: './tessdata'
}
});
(0, _child_process.execSync)(rm ${filePath});
return stdout.toString();
}`

[vladholubiev]

PRs are welcome!