Refactor `SignItCoreContent` for browser compatibility & modal init fix

[kabir-afk]

Changes

1. b9cf4f - Made a function to pass messages in order to adhere to DRY principle. Allows reusability while not cluttering the codebase and optimizes the message passing process.
2. 6505f6 - Refactored the way SignItCoreContent.js received banana such that it is universal to both Chrome and FF.
3. 557293 - Initialized modal every time when signit.hintIcon message was passed rather than calling it only when popup was undefined.

Description

• I'll start with the 2nd change since first change is self explanatory.

  Issue: Earlier I was type checking the browser using conditionals for the desired changes and that was also because , when arguments were passed in the SignItCoreContent() constructor function , it received banana's sourceMap as an instance of Map in Firefox and as Object in Chrome.

  While this worked it passed unnecessary messages in background-script.js and made for an undesirable code overall.

  Solution: I stored the sourceMap inside browser.storage.local and later passed it as argument whenever constructor function was in use. This is compatible with both Chrome and Firefox and I think it overall makes for a better code.

• 3rd change is a potential fix for challenges faced after #71

  Issue: After passing messages from popup.js to both sw.js and background-script,js to execute functions (because we cant use backgroundPage as API namespace in MV3 unlike FF), the way UI language was being updated is buggy.

  • Firefox - In FF Popup UI updates immediately but for the changes to reflect in Modal whole web page has to be reloaded
  • Chrome - In Chrome Popup UI updates after it is toggled OFF then ON again , and same has to be done as FF to see changes in modal

  Solution: Whenever signit.hintIcon is executed (modal is activated) initModalUI function is called every time unlike earlier when it is called only when popup === undefined. While this is a temporary fix since things were somehow working fine before previous PR. By doing this at least page does not need to be reloaded.

[kabir-afk]

I forgot to mention that in background script I added extra regex to remove comma and other special characters inside getAvailableWord function