zpool should detect invalid fsproperty on create

[loli10K]

Motivation and Context

Fix #7620

Description

This change improve the handling of invalid filesystem properties when specified at pool creation: this is useful when 'zpool create -n' (dry run) is executed to detect invalid fs-level options (-O) before the actual command is run.

NOTE: this is still Work in Progress.

• Need to add test case to the ZTS (the only occurrence of zpool create -n i could find is in "zpool_create_003_pos.ksh": i should probably update the existing test case instead of adding a new one). EDIT: done
• Need to detect invalid dataset properties for volumes (zpool create -n -O volsize=<n> should fail). EDIT: done

How Has This Been Tested?

Manual run on local builder:

root@linux:~# POOLNAME='testpool'
root@linux:~# TMPDIR='/var/tmp'
root@linux:~# mountpoint -q $TMPDIR || mount -t tmpfs tmpfs $TMPDIR
root@linux:~# zpool destroy $POOLNAME
cannot open 'testpool': no such pool
root@linux:~# rm -f $TMPDIR/disk*
root@linux:~# truncate -s 128m $TMPDIR/zpool_$POOLNAME.dat
root@linux:~# 
root@linux:~# zpool create -n -O doesnotexist=on $POOLNAME $TMPDIR/zpool_$POOLNAME.dat
property 'doesnotexist' is not a valid filesystem property
root@linux:~# echo $?
1
root@linux:~# zpool create -n -O org.zfsonlinux:doesnotexist=on $POOLNAME $TMPDIR/zpool_$POOLNAME.dat
would create 'testpool' with the following layout:

	testpool
	  /var/tmp/zpool_testpool.dat
root@linux:~# echo $?
0

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the ZFS on Linux code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• All commit messages are properly formatted and contain Signed-off-by.
• Change has been approved by a ZFS on Linux member.

[codecov]

Codecov Report

Merging #7878 into master will increase coverage by 10.58%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##           master    #7878       +/-   ##
===========================================
+ Coverage   67.87%   78.45%   +10.58%     
===========================================
  Files         322      376       +54     
  Lines       97552   114006    +16454     
===========================================
+ Hits        66215    89449    +23234     
+ Misses      31337    24557     -6780

Flag	Coverage Δ
#kernel	78.8% <ø> (+40.48%)	⬆️
#user	67.52% <100%> (-0.22%)	⬇️

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