make conversion menus dynamic

[qnhn22]

Description

I utilized React hooks to make conversion Source and Destination fields dynamic (Once a source or destination is selected, it will be removed from the other menu). In addition, I removed meter units from destination field options.

Fixes #904

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Type of change

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• Note merging this changes the database configuration.
• This change requires a documentation update

Checklist

(Note what you have done by placing an "x" instead of the space in the [ ] so it becomes [x]. It is hoped you do all of them.)

• I have followed the OED pull request ideas
• I have removed text in ( ) from the issue request
• You acknowledge that every person contributing to this work has signed the OED Contributing License Agreement and each author is listed in the Description section.

Limitations

(Describe any issues that remain or work that should still be done.)

[huss]

Thanks to @qnhn22 for another contribution to OED. The code looks fine and trying it found it does what is desired without any issues. Good work and this is ready to merge.