Remove unnecessary length constraints from VARCHAR(N) columns

[sahibamittal]

Description

Create a database migration that converts VARCHAR(N) columns to TEXT to lift the artificial length constraints.
Keep the constraints for columns where the maximum value length is known, e.g. SHA256.

Addressed Issue

Closes DependencyTrack/hyades#1077

Checklist

• I have read and understand the contributing guidelines
• This PR fixes a defect, and I have provided tests to verify that the fix is effective
• This PR implements an enhancement, and I have provided tests to verify that it works as intended
• This PR introduces changes to the database model, and I have added corresponding update logic
• This PR introduces new or alters existing behavior, and I have updated the documentation accordingly

[nscuro]

Great work! Some additional changes are needed (inclusion of the new changelog file), and some are to be discussed I guess (whether or not to convert columns holding enum values to TEXT as well).

Sorry for the many comments.

In some model classes there are attempts to truncate strings in order to fit the previously used length constraints, e.g.:

hyades-apiserver/src/main/java/org/dependencytrack/model/Component.java

Lines 417 to 419 in 6af80d3

	public void setGroup(String group) {
	this.group = StringUtils.abbreviate(group, 255);
	}

In order to get actual use out of this change, those abbreviate calls should also be removed.

[nscuro]

Great work!