Additional TeX syntax support and direct web-compatible build outputs

[thatcomputerguy0101]

This is a fairly major update adding many additional TeX features in addition to adding two more build targets. The updated README has documentation on all of the new user-facing features, whereas the below list touches on those briefly but adds some notes about the internals.

New TeX features:

• Variable subscripts: a_b
• Custom symbols used in multiple places, such as greek letter variables (\alpha), and certain operators.
• Comparison operator support: \ne, <, \geq, etc...
• Functions with custom bases: \sqrt[3]{x}, \log_3{y}

Other improvements:

• Build scripts for, node outputs (CJS), web (ESM and browser), and all of the above added to package.json
• ES6 module and global variable script utilizing Webpack (both work directly in a web browser)
• Consistency improvements to parsing logic, such as with strings and symbols
• MathJS updated to v10.6.4, where the typing logic of nodes was improved allowing for more specific types utilized here.
• Formatting cleanup to reduce linter errors/warnings

[thatcomputerguy0101]

The build improvements in this PR cover a similar set of needs to #10, but using Webpack instead of Vite. Vite may be a better build system, so I'll split the parser changes in this PR apart from the build changes if that is accepted.

[thatcomputerguy0101]

I also believe this set of changes should also be compatible with MathJS 11, but not MathJS 12.

[davidtranhq]

Thanks so much for all of this! It looks great. I've updated the dependencies from some previous PRs so that the project uses MathJS 12 now: if you still want it to be merged feel free to make those changes so that the tests pass again!

[thatcomputerguy0101]

For the symbols test, do you prefer the unit test style of this PR, or the integration test style of #9? (Or both, but that seems excessive to me.)

[thatcomputerguy0101]

Superseded by #13 and #14.