Enable logical assignment by default in @babel/parser

Feature Request

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Logical Assignment (&&=, ||=, ??=) is Stage 4!

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This means that it should be enabled by default in @babel/parser 🎉

It should be done similarly to this commit: https://github.com/babel/babel/commit/c3388ea42f3ec2d9614503fd0eff81b679ba12a7

1. Remove all the this.hasPlugin and this.expectPlugin checks related to logicalAssignment in packages/babel-parser/src
2. Remove all the usages of logicalAssignment in @babel/parser’s tests
3. Probably there is a test to ensure that the plugin is required; it can be removed.
4. Move the tests from the experimental folder to es2021, create one if it doesn’t exist
5. PR! 🎉

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If it is the first time that you contribute to Babel, follow these steps: (you need to have make and yarn available on your machine)

1. Write a comment there to let other possible contributors know that you are working on this bug.
2. Fork the repo
3. Run git clone https://github.com/<YOUR_USERNAME>/babel.git && cd babel
4. Run yarn && make bootstrap
5. Wait ⏳
6. Run make watch (or make build whenever you change a file)
7. Add a test if needed (only input.js; output.js will be automatically generated)
8. Update the code!
9. yarn jest babel-parser to run the tests
   • If some test outputs don’t match but the new results are correct, you can delete the bad output.js files and run the tests again
   • If you prefer, you can run OVERWRITE=true yarn jest babel-parser and they will be automatically updated.
10. If it is working, run yarn jest to run all the tests
11. Run git push and open a PR!

[JLHwung]

@pustovalov Thanks for showing up. A good first issue targets to first-time contributors. That said, if it is not claimed by a new contributor in the next 24 hours, it will be yours!

[existentialism]

@vahnag no rush!