Add new file to type cache

[kislaykishore]

Description

Add new file to type cache

This avoids an additional list call in case of implicit-dirs.

Link to the issue in case of a bug fix.

NA

Testing details

1. Manual - NA
2. Unit tests - NA
3. Integration tests - NA

[codecov]

Codecov Report

Attention: Patch coverage is 73.68421% with 5 lines in your changes missing coverage. Please review.

Project coverage is 79.11%. Comparing base (577de7c) to head (9182b37).
Report is 39 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/fs/inode/base_dir.go	0.00%	4 Missing ⚠️
internal/fs/fs.go	87.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2303      +/-   ##
==========================================
+ Coverage   79.05%   79.11%   +0.06%     
==========================================
  Files         105      106       +1     
  Lines       11581    11574       -7     
==========================================
+ Hits         9155     9157       +2     
+ Misses       1960     1952       -8     
+ Partials      466      465       -1     

Flag	Coverage Δ
unittests	79.11% <73.68%> (+0.06%)	⬆️

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[raj-prince]

(a) (Out of scope of this PR) Currently type cache is guarded twice, one with dirInode lock another one with lru lock. We need to remove one.
(b) Can we write a concurrent test, stat and fileCreation.