Fix chamber env and chamber export -f dotenv

[mckern]

This was reported in #366: chamber made no effort to sanitize keys for either of these commands or formats, which can result in invalid variable names being used for both of these output formats. This PR fixes half of the problem (invalid characters in retrieved keys when rendered via env or export -f dotenv) but does not address the larger question of "what is a valid character when writing a key?"

Some of the construction of these formats have now been unified, with an optional boolean flag for env to preserve key case -- note that keys will still be sanitized, they just won't be converted to uppercase. Since export -f dotenv rewrites values using escape characters, I've made the choice to continue allowing export -f dotenv to always convert keys to uppercase.

New Flags

chamber env has received a couple of new flags: -e, --escape-strings, -p, --preserve-case :

• --escape-strings will allow chamber env to print values as either safely quoted string literals or safely quoted escape sequences.
• --preserve-case will force chamber env to respect whatever case a key originally used

Before

$ chamber env -b s3 --backend-s3-bucket dummy-bucket example-service
export EXAMPLE_PASSWORD=cafeface1337
export EXAMPLE-ACCESS-TOKEN=abcdefghijklmnopqrstuvwxyz
export EXAMPLE-USER=itsamemario
export EXAMPLE-MULTILINE='I have eaten
the plums
that were in
the icebox

and which
you were probably
saving
for breakfast

Forgive me
they were delicious
so sweet
and so cold
'

$ chamber export -f dotenv -b s3 --backend-s3-bucket dummy-bucket example-service
EXAMPLE_PASSWORD="cafeface1337"
EXAMPLE-ACCESS-TOKEN="abcdefghijklmnopqrstuvwxyz"
EXAMPLE-USER="itsamemario"
EXAMPLE-MULTILINE="I have eaten\nthe plums\nthat were in\nthe icebox\n\nand which\nyou were probably\nsaving\nfor breakfast\n\nForgive me\nthey were delicious\nso sweet\nand so cold\n'

After

$ chamber env -b s3 --backend-s3-bucket dummy-bucket example-service
export EXAMPLE_PASSWORD=cafeface1337
export EXAMPLE_ACCESS-TOKEN=abcdefghijklmnopqrstuvwxyz
export EXAMPLE_USER=itsamemario
export EXAMPLE_MULTILINE='I have eaten
the plums
that were in
the icebox

and which
you were probably
saving
for breakfast

Forgive me
they were delicious
so sweet
and so cold
'

$ chamber export -f dotenv -b s3 --backend-s3-bucket dummy-bucket example-service
EXAMPLE_PASSWORD="cafeface1337"
EXAMPLE_ACCESS-TOKEN="abcdefghijklmnopqrstuvwxyz"
EXAMPLE_USER="itsamemario"
EXAMPLE_MULTILINE="I have eaten\nthe plums\nthat were in\nthe icebox\n\nand which\nyou were probably\nsaving\nfor breakfast\n\nForgive me\nthey were delicious\nso sweet\nand so cold\n'

What about backwards compatibility?

Effort has been taken to preserve the spirit of backwards compatibility with the output formats that these commands have rendered in the past. But since the formats were objectively incorrect, I'm really not worried about it.

[alecjacobs5401]

Nice.

Nothing immediately glaring at me, but a few open questions.

Thanks for doing this @mckern! Having this be consistent it amazing

[alecjacobs5401]

I have really one comment repeated about a test case for when we're validating/sanitizing shell keys.

I have no strong feelings one way or another and this LGTM as is.

Thanks!