feat(files): add node status

[skjnldsv]

/** This is a new node and it doesn't exists on the filesystem yet */
NEW = 'new',
/** This node has failed and is unavailable  */
FAILED = 'failed',
/** This node is currently loading or have an operation in progress */
LOADING = 'loading',
/** This node is locked and cannot be modified */
LOCKED = 'locked',

Makes it a bit more official instead of those weird hidden values
e.g https://github.com/nextcloud/server/blob/4e60b3c61e8e0699e341fb62f9f109d2525be5ab/apps/files/src/services/Files.ts#L65

[codecov]

Codecov Report

Merging #744 (0e2754d) into master (af661f9) will increase coverage by 0.25%.
The diff coverage is 88.88%.

❗ Current head 0e2754d differs from pull request most recent head 55a2d9b. Consider uploading reports for the commit 55a2d9b to get more accurate results

@@            Coverage Diff             @@
##           master     #744      +/-   ##
==========================================
+ Coverage   77.41%   77.66%   +0.25%     
==========================================
  Files          17       17              
  Lines         394      403       +9     
  Branches      107      108       +1     
==========================================
+ Hits          305      313       +8     
- Misses         76       77       +1     
  Partials       13       13              

Files Changed	Coverage Δ
lib/files/node.ts	98.27% <85.71%> (-1.73%)	⬇️
lib/files/nodeData.ts	100.00% <100.00%> (ø)

[susnux]

👍