add juicefs directory quota function

[ldd91]

This pr is to add directory quota for juicefs,here is our design docs: https://docs.google.com/document/d/126-Pzijf4e-XjoslS5_kVDOvwh0LFwi_Mc96Tp74Cf8/edit#

[CLAassistant]

All committers have signed the CLA.

[sonarqubecloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
46 Code Smells

No Coverage information
19.8% Duplication

[millerlogic]

Hi, thanks for this. I am confused by the description,

This command provides a faster way to actively build cache for the target files. It reads all objects of the files and then write them into local cache directory.

This is not what I think of when I hear the term quota for a file system. I think either the description needs updating, or the command should be more specific, like cachequota or cquota. Otherwise can you let me know what I'm missing?
I say this without fully knowing what this PR does, I'm just commenting my confusion. Thanks

[davies]

@ldd91 We have took over this PR with #3268, thanks for your contribution!