feat: Make CTRL+S hotkey work for environment modal

[bacteriostat]

Description

Closes #1447

This PR makes CTRL+S hotkey work for environment modal. Here are the changes that I had to do:

1. The hotkey didn't have access to data of formik used in the environment modal, so the existing saveEnvironment(values, environmentUid, collectionUid) couldn't be used. So the first step was making it not accept values from dispatcher i.e., saveEnvironment(environmentUid, collectionUid).

2. Unlike other components (Collections, Requests) where redux states were updated as user edited them, EnvironmentVariables changes were only being tracked in formik. So the next step was to update the redux state of environments. There was already an incorrectly named saveEnvironment which updated the state but was not used. So I renamed it to updateEnvironment (as was the naming convention for other cases) and dispatched the changing form values to it.

3. Next I added a key called environmentSettingsSelectedTab inside collection's state to track which environment was being edited. This was necessary for saving.

4. environmentSettingsSelectedTab is updated using the action updateEnvironmentSettingsSelectedTab whenever the tab is switched.

5. Added toast to inform user that the environment has been persisted.

6. Passed isModified down to EnvironmentVariables to track changes and save only when there are actual changes.

Contribution Checklist:

• The pull request only addresses one issue or adds one feature.
• The pull request does not introduce any breaking changes
• I have added screenshots or gifs to help explain the change if applicable.
• I have read the contribution guidelines.
• Create an issue and link to the pull request.