Make shell commands support column qualifiers with colons

Revisiting abandonded HBASE-13788.

Problem

Shell commands do not support column qualifiers with colons (which are actually quite common in practice) because the part after the first colon is always treated as a converter expression.

This can be too restrictive because:

1. Converters are only used for get and scan commands. They are not supported anyway for other mutating commands such as put, delete, incr, etc.
2. Converter expression should follow a specific pattern. It should either be a method name of the Bytes class, or should be in c(CLASS).METHOD format. We ignore the part after the first colon even if it does not follow the pattern.

Suggested solution

I suggest applying two approaches to make the commands support column qualifiers with colons.

1. Do not interpret column qualifiers when using commands that don't support converters.
2. If the part after the first colon does not follow the pattern, treat it as a part of the column qualifier

Counterargument

Depending on how you see it, this makes the commands inconsistent in how they handle column qualifiers. For example, a user may want to use the same column expression throughout the commands.

create 't1', 'cf'

col = 'cf:cq:toLong'

# Expecting incr command to automatically ignore :toLong part
incr 't1', 'r1', col, 1

get 't1', 'r1', COLUMNS => [col]

However, if we see the converter as an option that is supported by only a few commands, passing it to a command that doesn't support it can be considered to be a user error. help 'put' or help 'delete' don't mention anything about converters.

Alternative solution

An alternative solution would be to add a global switch that disables the converter interpretation altogether.