add ability to set log level after logger is constructed

[shazron]

Description

Right now you have to set the log level via the constructor like so:

const aioLogger = require('@adobe/aio-lib-core-logging')('App', { level: 'info' })

function main (params) {
     // you can't set the log level here, it is already fixed to `info` above
    // thus .debug won't output anything
     aioLogger.debug('this will not output anything')
}

Proposed setLogLevel feature

const aioLogger = require('@adobe/aio-lib-core-logging')('App')

function main (params) {
    // the log level is by default `info` and you can't change it after construction,
    // unless you add this feature like so
    aioLogger.setLogLevel(params.LOG_LEVEL)
   // if params.LOG_LEVEL was 'debug', now debug logs will show in the output
   aioLogger.debug('this will output if params.LOG_LEVEL is debug')
}

Workaround

The workaround is to create the logger with the log level, in your function scope.

const coreLogger = require('@adobe/aio-lib-core-logging')

function main (params) {
    const  aioLogger = coreLogger('App', { level: params.LOG_LEVEL })
   // if params.LOG_LEVEL was 'debug', debug logs will show in the output
    aioLogger.debug('this will output if params.LOG_LEVEL is debug')
}