Allow dash in account name

[louisruch]

What does this PR do

Resolves #759
Relaxes the regex constraint to allow - (dash) as a valid character in an account login name

Testing

Updated unit tests
I verified that password do accept all characters mentioned in the issue (hyphen, underscore and period)
Performed manual testing:

Before changes:

boundary accounts create password -auth-method-id ampw_1234567890 -login-name admin-tester
Password is not set as flag, please enter it now (will be hidden):
Error from the controller when performing create on password-type account:
Error information:
  Code:                Internal
  Error ID:            YqlVyFuvqc
  Message:
  Status:              500

Server logs error:

2020-12-01T13:10:23.671-0800 [ERROR] controller: internal error returned: error id=YqlVyFuvqc error="unable to create user: create: password account: invalid login name; must be all-lowercase alphanumeric: invalid parameter: parameter violation: error #100"

After changes:

boundary accounts create password -auth-method-id ampw_1234567890 -login-name admin-tester
Password is not set as flag, please enter it now (will be hidden):

Account information:
  Auth Method ID:      ampw_1234567890
  Created Time:        Tue, 01 Dec 2020 13:08:55 PST
  ID:                  apw_jQ1DKAWgQk
  Type:                password
  Updated Time:        Tue, 01 Dec 2020 13:08:55 PST
  Version:             1

  Scope:
    ID:                global
    Name:              global
    Type:              global

  Attributes:
    Login Name:        admin-tester

[hashicorp-cla]

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