Standardize max_length globally across all models

[jathanism]

Proposed Changes

The max_length field varies widley. This grep catches most of it (with uniqueness counts):

$ grep -r " name = .*\models.CharField" nautobot | grep -o "max_length.*\d+" | sort -n | uniq -c
  37 max_length=100
   1 max_length=150
   1 max_length=20
   1 max_length=200
   2 max_length=255
   5 max_length=50
   7 max_length=64

Justification

This inconsistency causes recurring confusion in UX at a minimum, not to mention complicates testing and validation often enough to be a pain.

NB: This may be solved by the introduction of BasePropertiesModel or similar in #2822?

TODO

• Increase Device/VirtualMachine name limit to at least 80 chars (vSphere limit) #2603
• Increase VLAN name's max_length to 255 #3171

[bryanculver]

As long as max_length goes up this shouldn't be any hard requirement to solve in 2.0. And I don't know of any places where we'd like to make this length smaller.

[glennmatthews]

Need to also make sure the form fields and serializer fields also have the correct max_length.

[glennmatthews]

Should revisit this aspect of our data models more generally - does description need to be limited to 200 characters or should it also increase, etc.

[bryanculver]

Should consider CustomFieldChoice's value as well.

[lampwins]

The scope will be any CharField under 255 will move to 255.

[lampwins]

Probably want a constant in nautobot.core

[lampwins]

Will want to doublecheck forms and serializer fields

[glennmatthews]

Implemented by #5355.