Make instance logLevel setter able to process string input

[hsubox76]

When Firestore and other users of Logger set log level on their instance only, this change allows them to use string input in addition to LogLevel enums. Firestore has a public interface that takes string input (just as the top-level setLogLevel() does) and needs to use this input to set logLevel on the Firestore logger instance only.

[hsubox76]

Needed to make an additional setter method because built-in getters and setters are required to be the same type.

[google-oss-bot]

Binary Size Report

Affected SDKs

• @firebase/logger

  Type	Base (ac215cf)	Head (93b9e1c)	Diff
  esm2017	3.22 kB	3.25 kB	+23 B (+0.7%)
  main	5.09 kB	5.14 kB	+51 B (+1.0%)
  module	4.78 kB	4.83 kB	+51 B (+1.1%)

• firebase

  Type	Base (ac215cf)	Head (93b9e1c)	Diff
  firebase-analytics.js	26.5 kB	26.6 kB	+130 B (+0.5%)
  firebase-app.js	19.9 kB	19.9 kB	+58 B (+0.3%)
  firebase-database.js	187 kB	187 kB	+132 B (+0.1%)
  firebase-firestore.js	288 kB	289 kB	+130 B (+0.0%)
  firebase-firestore.memory.js	230 kB	230 kB	+130 B (+0.1%)
  firebase-performance-standalone.es2017.js	72.7 kB	72.7 kB	+35 B (+0.0%)
  firebase-performance-standalone.js	48.1 kB	48.2 kB	+58 B (+0.1%)
  firebase-performance.js	38.5 kB	38.6 kB	+130 B (+0.3%)
  firebase-remote-config.js	36.9 kB	37.0 kB	+130 B (+0.4%)
  firebase.js	822 kB	822 kB	+59 B (+0.0%)

Test Logs

• Base (ac215cf8): https://github.com/firebase/firebase-js-sdk/actions/runs/106103089
• Head (93b9e1c4): https://github.com/firebase/firebase-js-sdk/actions/runs/106123584

[Feiyang1]

Do you have the link to the Firestore PR?

[hsubox76]

Firestore PR: https://github.com/firebase/firebase-js-sdk/pull/3064/files