Meta: support `delete` env-ops in `*.ticat` or `*.ticat` meta file

[innerr]

Massive used currently:

[env]
sample-key-1 = read
sample-key-2 = may-read
sample-key-3 = write

Not frequently use:

[env]
sample-key-4 = may-write
sample-key-x = <op1> : <op2> : <op3> ...

Propose to add:

[env]
sample-key-n = delete
sample-key-m = read : delete